Self-retaining electrical contacts

A self-retaining electrically conductive contact suitable for use in insulated terminal blocks and connectors requiring a minimum of spaces between the conductive elements includes a first section which may be formed as a male or female element, a middle section provided with semi-circularly shaped ears which are sloped in a manner to guide the retaining ears around a retaining surface provided in an insulating member when inserted therein and retaining the contact therein once the contact is inserted in the insulated member. The other end section is formed to receive an electrical conductor thereon as required.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to electrical contacts, and more 
particularly, to a self-retaining electrical contact suitable for use in 
terminal blocks and connectors requiring minimum spacing between 
conductive elements. 
2. Discussion of the Relevant Art 
Many types of electrical contacts utilize protrusions or detent devices 
designed to cooperate with each other in order to retain the electrical 
contact in a housing or terminal block once inserted therein and require 
the use of a special tool if removal is required. Typical of this type of 
contact is disclosed in U.S. Pat. No. 3,842,396 issued to B. E. Olsson on 
Oct. 15, 1974. The device disclosed therein utilizes a tapered contact 
element having a pair of ears thereon that are adapted to compress when 
inserted through an aperture provided to receive the contact. Upon the 
contact reaching the desired position, the contact ears are permitted to 
expand to its original position in a slightly larger aperture provided and 
therefor the contact cannot be withdrawn since the inwardly protruding 
shoulder of the first aperture retains the contact in position. As 
constructed, the second aperture must be larger than the first in order to 
provide the necessary retaining shoulder or surface. 
Another type of retaining structure is disclosed in U.S. Pat. No. 3,963,302 
issued to C. A. Gourley on June 15, 1976. Disclosed therein is an 
electrical socket contact which is provided with a pair of extending ears 
generally lying in the same plane as the rear surface of the contact. The 
ears are sloped so that the narrower portion thereof is inserted first 
into an aperture provided in a suitable insulated member. Additional slots 
are provided on the side of the insulated member and, as the contact is 
inserted therein from the top surface, the ears are guided into the slots 
provided on the side of the insulated member and receive the ears therein 
by a flexing of the housing wall. Once the ears are disposed within the 
slots provided, withdrawal of the contact is restrained by the ears 
extending into the slot and are retained by the wall of the insulated 
member. 
A different retaining mechanism is disclosed in U.S. Pat. No. 4,043,631 
issued to R. Lapes on Aug. 23, 1977. The contact disclosed therein is 
provided with a pair of inwardly disposed recesses on narrowly extending 
feet of the contact. The narrowly extending feet are resilient and, when 
inserted into an insulated member provided with an aperture therefor, flex 
towards each other permitting the inwardly extending recesses to be 
inserted into an insulated member beyond inwardly extending mated 
protrusions provided in the aperture. When in position, the recesses on 
the contact return to their original position encompassing the protrusions 
and, thus, retain the contact in position in the insulated member. Mating 
with a cooperating contact is accomplished by lateral movement of the 
mating circuit. 
The instant invention has been designed to overcome the shortcomings of the 
prior art by providing a simple self-retaining electrically conductive 
contact that utilizes a minimum of space permitting tight packaging and 
proximity of the electrical contacts without requiring lateral motion by 
the mating device. 
SUMMARY OF THE INVENTION 
Therefore, the instant invention has been designed to overcome the 
shortcomings found in the prior art which require additional space for the 
retaining mechanism and/or require lateral movement of the connector for 
contact purposes. 
Therefore, it is an object of the present invention to provide a 
self-retaining electrical contact suitable for use in terminals and 
connectors requiring close proximity between the contacts. 
It is another object of the present invention to provide a simple, 
inexpensive, electrical contact terminal that is self-retaining. 
It is yet another object of the present invention to provide a 
self-retaining electrical contact that does not require additional space 
to accomodate the self-retaining feature. 
Yet another object of the present invention is to provide a self-retaining 
contact which may be made of the male or female type. 
The foregoing and other objects and advantages will appear from the 
description to follow. In the description, reference is made to the 
accompanying drawing which forms a part hereof, and on which is shown, by 
way of illustration, specific embodiments in which the invention may be 
practiced. These embodiments will be described in sufficient detail to 
enable those skilled in the art to practice the invention, and it is to be 
understood that other embodiments may be utilized and that structural 
changes may be made without departing from the scope of the invention. The 
following detailed description is, therefore, not to be taken in a 
limiting sense, and the scope of the present invention is best defined by 
the appended claims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the figures and, in particular, to the FIGS. 1 through 4, 
there is shown a plurality of self-retaining electrical contacts 10 
inserted in an insulated terminal board 12 that is provided with a 
plurality of bore holes or apertures 14 suitable for receiving the 
self-retaining contacts therein. The self-retaining electrical contacts 10 
are shown greatly enlarged in the remaining figures. The terminal board 
12, preferably utilized in the instant invention, is manufactured from an 
insulating material manufactured by the General Electric Company, 
Syracuse, N.Y., and known by the trade name of LEXAN. 
The bore holes 14 provided in terminal board 12 are lined in a closely knit 
pattern specifically for receiving miniaturized overvoltage line 
protectors utilized in the telephone central office to protect the 
equipment connected thereto. A typical line protector is disclosed in U.S. 
Pat. No. 4,424,546 to T. J. Smith, issued Jan. 3, 1984 and entitled 
MINIATURE CENTRAL OFFICE SURGE PROTECTORS. Although a terminal board has 
been disclosed herein as being the preferred embodiment, it is obvious to 
those knowledgeable in the art that the self-retaining electrical contacts 
disclosed herein may be utilized in connector assemblies as well as the 
terminal board disclosed herein. 
The remaining wall 16, at the bottom of the bore hole 14, is provided with 
a semi-circularly shaped slot or aperture 18 through which the electrical 
contacts 10 are inserted. The upper surface 20 and lower wall portion 22 
of the remaining wall 16 function as a retaining surface for the contact 
10 as will be explained hereinafter. 
The terminal board 12 is also provided with a pyramidally-shaped protrusion 
24 which cooperates with the base of the miniature surge protectors and 
helps in alignment of the mating male conductor pins, not shown, when the 
surge protector assemblies are inserted into the terminal board. 
The terminal board 12 is also provided with holes 26 and 28 for easier 
mounting to a surface. The terminal board as disclosed is manufactured in 
a conventional manner by injection molding and all of the apertures and 
protrusions are formed in the mold and it only remains for the contacts 10 
to be inserted therein to complete the assembly. 
Referring now to FIG. 5 which discloses an enlarged self-retaining 
electrical contact 10 suitable for insertion in the terminal board 12. The 
contact 10 is provided with an elongated end section 30 having three 
fingers 32, 34, and 36 preferably disposed 120 degrees apart with slots 
38, 40 and 42 provided therebetween so that a male pin conductor inserted 
in the circularly-shaped opening 44 may cause them to flex to receive the 
male contact, not shown, and be retained therein by the dimpled portions 
46, 48 and 50 provided proximate the distal ends of each of the fingers 
32, 34 and 36. 
The contact 10 is provided with a middle section 52 having a pair of 
outwardly extending ears 52 and 56 which are disposed transverse to the 
longitudinal axis 58 of the contact. When viewed in cross-section, as 
shown in FIG. 6, the ears 54 and 56 are seen to be generally 
semi-circularly shaped. The distal ends 60 and 62 of ears 54 and 56 are 
sloped in an inwardly direction towards end section 30 of the contact 10 
at an angle phi (.phi.) of between 5 and 30 degrees, preferably 10 
degrees, relative to the longitudinal axis 58. The ears 54 and 56 because 
of their preferred shape, function as a guiding and retaining means by 
permitting the leading edges 64 and 66 of ears 54 and 56, respectively, to 
flex around the remaining wall 16 appearing at the bottom of bore holes 14 
when contact 10 is inserted therein. Since the rear or trailing edges 68 
and 70 are smaller in diameter than the lower surface 22 of the remaining 
wall 16, the contact 10 having passed beneath the wall will be prevented 
from moving out of bore hole 14 by the ears 54 and 56, which will be 
explained in more detail hereinafter. The middle section 52 is 
additionally provided with an additional guiding portion 72 that is 
semi-circularly shaped and positions the contact 10 in the slot 18 
permitting the leading edges 74 and 76 of fingers 32 and 34 to sit on the 
upper surface 20 of wall 16, thereby preventing the contact 10 from 
passing completely through the bore hole 14 when a mating connector is 
inserted therein. Slots 78 and 80 are cut in the middle section 52 in 
order to permit the sloping of the distal ends 60 and 62 of ears 54 and 
56. 
The contact 10 also includes a second end section 82 which is generally 
elongated and may be formed with a concave or convex surface as shown in 
FIGS. 6a and 6b to increase its strength. End section 82 may be utilized 
with a wire wrapping tool or by soldering electrically conductive wire 
thereto in a conventional manner. Preferably the contact is manufactured 
from phosphor bronze or beryllium copper with a tin plate thereon but may 
be fabricated from any other suitably resilient electrically conductive 
material. 
Referring now to FIGS. 8 and 9, there is disclosed an alternative 
embodiment 84 of the instant invention. The mating end section 86 thereof 
is formed with three fingers 88, 90 and 92 with the distal ends thereof 
bent inwardly forming an essentially closed or male end 94 which may be 
received by a female receptacle provided in a contact such as that 
disclosed hereinbefore. Here again, preferably, the fingers are displace 
120 degrees and are provided with slots 96 therebetween. 
The middle section 98 of embodiment 84 is constructed identical to the 
middle section 52 of contact 10. The outwardly extending ears 100 and 102 
are angled at an inwardly direction towards the mating end section 86 at 
an angle phi (.phi.) to the transverse axis 104 which, preferably, is 10 
degrees and may be as large as 30 degrees. 
The other end section 106 is provided with a U-shaped longitudinally 
extending portion having an elongated slot 108 disposed therein, of a 
predetermined diameter suitable for retaining an electrically conducting 
wire therein, which may be permanently affixed by conventional soldering 
techniques. 
Referring now to FIGS. 10, 11, and 12, there is disclosed an enlarged 
cross-sectional view of the embodiment 10 being inserted into an insulated 
member or terminal board 12. The contact 10 is guided into bore 14 by 
means of end section 82 being inserted into the semi-circularly shaped 
slot 18. As the contact 10 is depressed further into the bore, the ears 54 
and 56 are guided over the remaining wall 16 at the bottom of bore 14, 
expanding thereover as the contact 10 is inserted all the way into the 
insulated member 12. Upon ears 54 and 56 extending to the lower surface 22 
of wall 16, the trailing edge 68 and 70 of ears 54 and 56 return to their 
original position and come into contact with surface 22 thereby preventing 
the contact 10 from being removed from the insulated material 12 if a 
force should be exerted on contact 10 in an upwardly direction, such as 
that caused by removing a mating male contact. The auxiliary guiding 
portion 72 seats the contact around the wall 16 while it is positioned in 
the semi-circular shaped slot 18 and prevents rotation of the contact in 
the bore hole 14 together with the pre-formed shape of the end section 82. 
Hereinbefore has been disclosed a self-retaining electrical contact 
suitable for use in a terminal board or connector requiring close 
proximity of the electrical contacts. It will be understood that various 
changes in the details, materials, arrangement of parts and operating 
conditions which have been herein described and illustrated in order to 
explain the nature of the invention, may be made by those skilled in the 
art within the principles and scope of the instant invention.