U.S. patent number 3,601,776 [Application Number 04/826,139] was granted by the patent office on 1971-08-24 for electrical connectors.
This patent grant is currently assigned to Symbolic Displays. Invention is credited to Gerald A. Curl.
United States Patent |
3,601,776 |
Curl |
August 24, 1971 |
ELECTRICAL CONNECTORS
Abstract
This invention relates to improvements in electrical connectors.
A two circuit jack and plug are described in which the jack is
formed of a series of sleeves inserted one within the other to
expose, at one end of the jack, a pair of contacting rings. The
contacting rings are noncircular in that their sidewalls are flat
at spaced points around their periphery. They are held in
encompassing ring retainers having inner dimensions to squeeze the
contacting rings such that they are more nearly circular. The jack
is associated with a phonograph type plug whose outer contact is
arranged to have its outer surface, rather then its inner surface,
mate with a respectively associated one of the contacting rings of
the jack.
Inventors: |
Curl; Gerald A. (N/A, CA) |
Assignee: |
Displays; Symbolic
(CA)
|
Family
ID: |
25245808 |
Appl.
No.: |
04/826,139 |
Filed: |
May 20, 1969 |
Current U.S.
Class: |
439/675; 403/332;
439/825; 24/619; 439/581; 439/842 |
Current CPC
Class: |
H01R
24/42 (20130101); H01R 2103/00 (20130101); Y10T
24/4555 (20150115); Y10T 403/62 (20150115) |
Current International
Class: |
H01R
13/00 (20060101); H01R 13/646 (20060101); H01R
017/04 (); H01R 013/12 () |
Field of
Search: |
;339/59,61,177,205,213,256,259 ;24/213,216,217,23SL,230
;287/126,58CT ;308/26 ;16/2 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Leppink; James A.
Assistant Examiner: Staab; Lawrence J.
Claims
Although I have shown and described certain specific embodiments of
my invention, I am fully aware that many modifications thereof are
possible. My invention, therefore, is not to be restricted except
insofar as is necessitated by the prior art and by the spirit of
the appended claims.
1. An electrical connector comprising a combination;
a contacting ring of electrically conductive, resilient, material
formed, in the relaxed condition of the ring, about a central axis
such that alternating sections of its inner peripheral surface lie
beyond, and alternating intervening sections thereof lie within,
the circle defined by the average distance from said axis to inner
peripheral surface; and
a circular ring retainer encompassing the outer peripheral surface
of the ring and having dimensions to force said ring against its
renitence to more nearly circular shape in which such alternate
sections lie less far beyond, and said alternate intervening
sections lie less far within, said circle than in the relaxed
condition of said contacting ring.
2. The invention defined in claim 1 in which all portions of the
inner peripheral surface of said ring, when assembled with said
ring retainer, are bowed on an arc having a center on the side
thereof toward said central axis.
3. The invention defined in claim 2 in which said contracting ring
comprises at least three sections whose inner peripheral surface
lie beyond, and a like number of sections whose inner peripheral
surface lie within, said circle.
4. The invention defined in claim 3 in which at least one annular
portion of said ring is continuous in a plane normal to said
central axis.
5. An electrical connector comprising a combination:
a contacting ring of electrically conductive, resilient material
formed, in the relaxed condition of the ring, about a central axis
such that alternating sections of its inner peripheral surface lie
beyond, and alternating intervening sections thereof lie within,
the circle defined by the average distance from said axis to inner
peripheral surface;
a ring retainer encompassing the outer peripheral surface of the
ring and having dimensions to force said ring against its renitence
to more nearly circular shape in which such alternate sections lie
less far beyond, and said alternate intervening sections lie less
far within, said circle than in the relaxed condition of said
contacting ring;
all portions of the inner peripheral surface of said ring, when
assembled with said ring retainer, being bowed on an arc having a
center on the side thereof towards said central axis;
said contacting ring comprising at least three sections whose inner
peripheral surface lie beyond, and a like number of sections whose
inner peripheral surface lie within, said circle;
at least one annular portion of said ring being continuous in a
plane normal to said central axis; and
a second contacting ring having a structure like that described for
the first mentioned contacting ring and which further comprises a
second ring retainer having a structure like that described for the
ring retainer first mentioned; said second ring retainer having a
central axis coincident with said central axis of said first
mentioned ring and ring retainer.
6. The invention defined in claim 5 in which said second ring and
said second ring retainer are smaller in diameter than the first
mentioned ring and ring retainer, respectively, and have an annular
portion in said plane normal to said axis.
7. The invention defined in claim 6 in which said second ring
retainer is formed of electrically nonconductive materials and has
outer diameter in said plane sufficiently small to clear said
contacting ring first mentioned.
8. The invention defined in claim 7 in which said second ring is
formed at one end of a rod, in which said second ring retainer
comprises a sleeve surrounding said rod; in which said ring first
mentioned comprises a sleeve surrounding said second ring retainer;
and in which said ring retainer first mentioned comprises a sleeve
formed of electrically nonconductive material surrounding said ring
first mentioned.
9. The invention defined in claim 8 which further comprises a male
connector including a cylindrical sleeve of electrically conductive
resilient material having an outer radius greater than the distance
from said central axis of the ring and ring retainer first
mentioned to the inner peripheral surface of said alternate
intervening sections of said ring when encompassed by said ring
retainer but less than that of said circle.
10. The invention defined in claim 1 which further comprises a male
connector including a cylindrical sleeve of electrically conductive
resilient material having outer radius greater than the distance
from said central axis to the inner peripheral surface of said
alternate intervening sections of said ring when encompassed by
said ring retainer but less than that of said circle.
11. The invention defined in claim 10 in which said cylindrical
sleeve of electrically conductive material terminates at a marginal
edge having outer radius less than the distance from said central
axis to the inner peripheral surface of said alternate intervening
sections of said ring when encompassed by said ring retainer.
Description
This invention relates to improvements in electrical connectors and
in particular it relates to improvements in connectors of the kind
in which contact is maintained by friction.
In those instances and applications where it may be necessary to
disconnect and reconnect an electric circuit from time to time, it
is desirable to employ an electrical connector in which the
connecting elements are maintained in electrical contact by
utilizing the force of friction between them. Such connectors are
usually divided into male and female parts which are mated by
sliding the surface of one part along the surface of another until
the parts overlap over a sufficient area to assure adequate
electrical contact. To produce connectors of this kind in which
electrical connection does not fail with time and which will
reliably complete an electrical connection after repeated
disconnections has proven to be quite difficult. Friction
connectors are produced in a wide variety of designs many of which
attempt to overcome the difficulty, at least in part, by the use of
resilient materials or other biasing means intended to maintain the
contact members in electrical contact. Sometimes, as for an example
in the case of cable connectors, an attempt is made to maintain
contact by screwing or otherwise fastening together the structures
in which the two contacting members are housed.
The problem is complicated because the choice of materials
sometimes is limited by environmental conditions and by the
frequency and by the magnitude of the electrical currents to be
passed through the connector. Attempts to solve the problem of
reliability and to find an acceptable compromise between cost and
reliability have produced a very wide variety of designs which are
successful in varying degree. Nonetheless improved connectors are
needed. Failure of an electric circuit can have a costly, dangerous
and sometimes even catastrophic effect. This possibility coupled
with the fact that electrical connectors have proven to be one of
the least reliable of all the electrical circuit elements, makes
the problem a serious one in which any improvement is
important.
It is the object of the invention to provide a novel connector of
the friction-type which overcomes some of the difficulties that
have gone unsolved in prior devices. It is an object of the
invention to provide a friction connector which utilizes the
resilience of the connector material in a novel fashion and which
avoids excessive stress at any point of the connector whereby to
minimize failure resulting from fatigue or from stressing a
connector part beyond its yield point. Failure occasioned by
stressing connector parts beyond their yield point is a rather
common occurrence occasioned in part by variation in manufactured
dimension from part to part. This difficulty is multiplied because
the mating parts of the connector may have been produced by
different manufacturers. Accordingly, among the objects of the
invention is to provide a connector one of whose elements is
arranged so that it can accommodate a mating connector whose
dimensions fall within a wide tolerance range.
Other objects of the invention are to provide a connector structure
in which the parts can be mated by relative motion between the
mating parts in one direction only and which requires no
orientation in other than that one direction. A related object is
to provide a connector useful in interconnecting coaxial conductors
and in which the advantages of the invention are realized in the
connection structure of both of the conductors. Another object is
to provide an improved connector to mate with a "phonograph jack"
in an arrangement in which both the inner an outer contact of the
phonograph jack serve as male connection elements. Thus it is an
object of the invention to provide an improved jack and plug
connector.
Certain of these and other objects and advantages of the invention
are realized by the provision of an electrical connector which
includes a contacting ring of electrically conductive resilient
material formed, in its relaxed condition, about a central axis
such that alternating sections of its inner peripheral surface lie
beyond, and such that alternate intervening sections thereof lie
within, an imaginary circle defined by the average distance from
the central axis to that inner peripheral surface; and by the
provision of a ring retainer structure which encompasses the outer
peripheral surface of the ring and has a dimension to force the
ring against its renitence to more nearly circular shape in which
the alternate sections of the inner peripheral surface lie less far
beyond, and so that the said alternate intervening sections lie
less far within, said circle than in the relaxed condition of the
ring.
In the drawings:
FIG. 1 is a cross-sectional view taken on the vertical centerline
through an electrical connector plug and jack in which the
invention is embodied;
FIG. 2 is a bottom plan view of the electrical connector jack shown
in FIG. 1;
FIG. 3 is a view in side elevation of the connector plug of FIG. 1
shown disassembled from the plug, which is shown fragmented and
partly in side elevation and partly in a cross section;
FIG. 4 is a top plan view of the outer contacting ring employed in
the embodiment illustrated in FIGS. 1, 2, and 3;
FIG. 5 is a top plan view of the inner contacting ring employed in
the embodiment illustrated in these drawings.
Referring to FIG. 1 of the drawing, the connector assembly there
shown comprises a jack designated generally by the reference
numeral 10 and a plug which is identified by the reference numeral
12. In this embodiment the plug and jack are arranged so that two
circuits leading to the plug are interconnected with two electrical
circuits leading to the jack. The female connector for both
circuits is housed in jack 10 and the male connector for both
circuits is formed by the structure of plug 12. The inner circuit
is completed through the electrical contact between the split
center pin 14 and inner contacting ring 16. The other circuit is
completed by interconnection between split wall, cylindrical
contact 18 and the outer contacting ring 20.
The inner contacting ring 16 is formed at one end of an elongated
rod or pin 22 which is bored axially for a distance from its
opposite end. The bore is threaded to receive the threads of a
terminal screw 24. Both the pin rod 22 and the inner contacting
ring 16 are formed of an electrically conductive material, such for
example as a copper or brass, whereby an electric circuit is
completed from the contacting ring 16 to the terminal screw 24 and
any conductor that may be clamped in electrical contact with the
pin 22 by the screw.
Pin 22 fits within a sleeve 26 formed of electrically insulating
material. The portion of sleeve 26 which surrounds the inner
contacting ring 16 is called a ring retainer and this portion is
designated by the reference numeral 28. The sleeve 26 fits within
another sleeve 30 formed of electrically conductive material. At
one end, the upper end in FIG. 1, the sleeve 30 fits tightly around
the sleeve 26 but at its other end, the lower end in FIG. 1 sleeve
30 has increased inside diameter to clear the ring retainer portion
28 of sleeve 26 and provide an annular space 32. The space 32
separates ring retainer 28 from the lower end of sleeve 30. This
lower end of sleeve 30 is designated by the reference numeral 20
and is the outer contacting ring described above.
The sleeve 30 is encompassed by a tightly fitting sleeve 34 the
lower end 36 of which functions to restrain and shape the outer
contacting ring and is called a ring retainer for the outer
contacting ring 20. In this embodiment the sleeve 34 and its ring
retainer section 36 are formed of electrically insulating material.
Insulation is not required where it is permissible or desirable
that the outer contacting ring be connected electrically to the
panel or chassis on which the connector assembly is mounted. This
embodiment is arranged so that the contacting rings will be
insulated from the chassis or panel. The ring 34 is encompassed by
a sleeve 38 the lower margin of which is provided with an outwardly
extending flange 40. The exterior of the sleeve 38 is threaded to
accommodate a nut 42 and a washer 44. This unit is intended for
mounting in a panel hole or a chassis hole having diameter less
than the diameter of the flange 40, and at least as great as the
diameter of the threaded sleeve 38. The unit is mounted so that the
flange 40 abuts the opposite face and is held by the nut 42. Sleeve
34 is made of a plastic material molded around the threaded sleeve
38 to form a high strength insulator of low dielectric constant.
The inner diameter of the sleeve 34 is smaller whereby the wall
thickness of the sleeve is increased above the point where the
sleeve 30 has increased diameter to form the outer or larger
contacting ring 20. The increase in diameter of the sleeve 30
occurs at a shoulder 46 which serves as a locating surface to limit
the degree of insertion of sleeve 30 within the sleeve 34. In
addition, this shoulder 46 serves as a support for a compressive
load applied in making electrical connections to sleeve 30 and the
outer contacting ring 20. Another supporting shoulder for the
sleeve 34 is provided by the upper end by sleeve 38. A washer 50 of
electrically collective material overlies the upper end of the
sleeve 34 an is staked in that position by upsetting the material
of the sleeve 30 immediately above the washer 50 as shown at point
52 in FIG. 1. Electrical connection to sleeve 30, and thereby to
the contacting ring 20, is made by clamping a conducting wire or
terminal device around the sleeve 30 and against the washer 50.
This is accomplished by turning down the nut 52 to compress the
external conductor between the washer 50 on one side and the flat
washer 54 on the other. A lock washer 56 is interposed between the
nut 52 and the flat washer 54 to make the connection more secure.
The upper end of the sleeve 30 is threaded to receive the threads
of nut 52.
The outermost sleeve 38 is held against axial movement relative to
the insulating sleeve 34 because the latter is molded such that
portions of it lie above and below the sleeve 38. The sleeve 34 is
held against motion relative to the sleeve 30 by being abutted
against the sleeve 30 at shoulder 46 and by having the sleeve 30
upset at point 52 against the washer 50. Also, provision is made to
assure against relative motion in the axial direction between the
sleeves 30 and 26 and the pin 22. At its upper end the pin 22 has
increased diameter to form a shoulder 60 against which the upper
end of sleeve 26 abuts. Similarly, the upper end of sleeve 26 has
increased diameter to form a shoulder 70 against which the upper
end of sleeve 30 abuts. Relative motion in the opposite direction
is precluded in this embodiment by forming a midregion of the pin
22 with reduced diameter and by upsetting or extruding the sleeves
30 and 26 inwardly into the space formed at that reduced diameter
section 72. This construction is generally designated by reference
numeral 74 in FIGS. 1 and 3.
The pin 14 of the plug is generally cylindrical and has a rounded
end to facilitate its insertion into the inner contacting ring. It
is slotted throughout its length and is formed of a resilient
material so that the two halves of the pin thus formed may be
squeezed together to permit their insertion into the inner
contacting ring when the parts are dimensioned on the high side of
their manufacturing tolerance.
The pin 14 is integrally formed with, and extends upwardly from,
the center of a cup-shaped base structure 78. The sidewall of the
cup extends upwardly in the direction of the pin and terminates at
its upper lip in an outwardly extending flange. Diametric portions
of the cup are cut away on parallel planes equidistant from the
center axis of the cup whereby the flange at the upper rim of the
cup sidewalls is reduced to a pair of projections extending in
opposite directions from the pin, one of which is designated 80 and
the other of which is designated 82 in the drawing. An inner lining
84 of insulating material encircles the lower end of the pin 14,
the bottom inner wall of the cut 78, and the inner surfaces of the
sidewalls of the cup. The insulating lining 84 is cup shaped. It
fills the space left by the cutaway portions of the cup 78 and is
visible at the exterior of the plug as shown in FIG. 3.
A retaining ring 86 is disposed within the insulating cup 84 with
its outer peripheral surface in engagement with the outside
sidewalls of the insulating cup 84. Complimentary conformations in
the outer peripheral surface of the ring 86 and the inner
peripheral surface of the sidewall of the lining 84 insure
retention of the ring within the lining. The inner peripheral
surface of the retaining ring 86 is threaded to receive the
external threads formed on the hollow shank 90 of the contact
structure of which the cylindrical contact 18 is a part. Shank 90
has dimensions to fit within the annular space between the inner
peripheral surface of retaining ring 86 and the outer peripheral
surface of the portion 92 of the cup 84 which encompasses the lower
end of pin 14. The shank 90 extends downwardly from a flange 94
which lies in a plane perpendicular to the axis of the plug. This
flange is integrally formed with shank 90 and with the cylindrical
contacting member 18.
The plug 12 is arranged for mounting upon a circuit board.
Electrical connection from the pin 14 to appropriate conductor runs
on the face of the circuit board are made through the cup 18 and
the projections 80 and 82. Another pair of projections extend
laterally outward from the ring 86 through the insulating liner 84
at the sides where the cup 78 is cut away. These other two
projections overlie other circuit runs of the circuit board and are
formed in the same plane as are the projections 80 and 82. One of
these two projections is visible in FIG. 3 where it is designated
by the reference numeral 96.
As best shown in FIG. 3, in the preferred construction the inner
contacting ring 16 does not extend to a point flush with the lower
face of the connected jack. Instead it ends at a point removed from
that face although in the preferred form, as shown, the inner
contacting ring 16 lies within the outer contacting ring 20. This
arrangement serves to insure that the inner contacting ring 16 will
not be short circuited by elements of the plug to the structure
which supports the contact sleeve 18. In addition it helps to
insure that the smaller and less rugged innner contacting ring and
its ring retainer sleeve are protected from damage. The pin 14 of
the plug extends beyond the end rim of the sleeve 18 in a degree
which depends upon the distance from the lower face of the jack to
its inner contacting ring and which depends also upon whether it is
the center contact or the outer contact that is to be first broken
and first made upon disconnection and reconnection of the plug and
jack.
The connector relies upon frictional engagement between pin 14 and
the inner contacting ring 16 and between the sleeve 18 and the
outer contacting ring 20 to accomplish electrical connection and to
maintain mechanical connection. The resilience of the contacting
rings and of the pin 14 and sleeve 18 is utilized to maintain the
frictional contact. The resilience of the contacting members is
utilized by forming them so that they may be deformed, and are
deformed, when the connection is made. By their renitence the
several contacting parts exert a force in opposition to that
deformation and that force is utilized to maintain frictional
contact between the pairs of mating connector parts. In the
invention this principle is employed in a special way. One of the
connector elements of a pair has the form of a connector ring which
is made of resilient material. Further, the contacting ring is
formed about a central axis and alternating sections of the ring,
or at least of its inner peripheral surface, lie beyond the circle
defined by the average distance from that central axis to the inner
peripheral surface of the ring. Alternate intervening sections of
the inner peripheral surface of the ring lie within that circle. A
contacting ring may be formed from a cylindrical sleeve by
deforming the sidewalls of the cylinder around the periphery so
that flattened sections are created. These flattened sections may
be flat but advantageously are bowed in a large diameter arc. The
sidewall of this ring is advantageously curved between the
flattened sections and sharp corners between successive flattened
sections are to be avoided. The contacting ring being thus formed
in its relaxed condition, may be treated and advantageously is
treated to remove internal stresses. The two contacting rings
employed in this embodiment are shown in this condition in FIGS. 4
and 5. FIG. 4 is a top plan view of the contacting ring 20 and
sleeve 30 of which it is a part. FIG. 5 is a top plan view of the
inner contacting ring 16 and the pin 22 of which it is a part.
These elements are shown in FIGS. 4 and 5 to have the relaxed shape
they have prior to being assembled within their respective ring
retainers and to which they tend to return upon being disassembled
from their respective ring retainers. The ring retainers encompass
the contacting rings and have dimensions attending to force these
portions of the exterior peripheral surface of the rings which
extend at greatest distance from the central axis of the rings
inwardly toward that axis. In effect, the retaining rings squeezes
the contacting ring and makes it more nearly round so that the
flattened portions of the ring are caused to bow outwardly forming
a smaller diameter arc whose center is on the side of the ring
section toward the central axis of the ring. The result is that the
contacting ring has a shape which approaches being cylindrical but
which is not quite cylindrical in that spaced points around its
inner periphery are closer to its central axis than are intervening
points. When a plug formed by a cylindrical contacting member
having outside diameter greater than the distance from the central
axis of the contacting ring to its sections closest to the axis is
forced into the ring, it will bear upon those sections of the inner
surface of the contacting ring and push them outwardly in a
direction tending more nearly to force the contacting ring to
circular shape. The greater the outer diameter of the mating plug
part, the greater will be the area of contact between the two
parts.
To facilitate insertion of the mating plug parts into the
contacting rings, the plug is advantageously formed with a smaller
outer dimension at points where it first begins to enter the
contacting ring. It is for this reason that the forward end of the
plug pin 15 is rounded and it is for this reason that the forward
end of the sleeve 18 of the plug is tapered inwardly at 98 so that
it will have a smaller diameter at its upper margin. The inner
diameter of the ring retainers are related to the dimensions of the
other respectively associated rings so that the contacting rings
can be forced to assume a perfectly circular form. Advantageously,
as in the embodiment illustrated, the plug members are formed so
that they too can yield whereby both elements of a contact pair are
made to deform. This reduces the possibility that one of them will
be deformed beyond its yield point.
It is not essential that the contacting rings be formed integrally
with the sleeve leading to the external connections structure as
shown in this embodiment although that construction is preferred.
Similarly it is not essential that the ring be continuous. The
contacting ring may be formed as a split ring although a continuous
ring is preferred so that the points of maximum stress will be
equally spaced around the periphery. In certain applications of the
invention it may be advantageous to employ a partly slotted ring to
facilitate initial insertion but limiting the degree of slotting so
that at least one annular portion of the ring is continuous in a
plane normal to the central axis.
The insulating material employed in the inner ring retainer in this
embodiment must have considerable hoop strength, must be a good
electrical insulator, and have a reasonably low dielectric
constant. A number of materials are suitable. One of them is
polysulfone. The ring retainer 34 in this embodiment is supported
by the encompassing sleeve 38 so that its hoop strength may be
considerably less. Consequently, a greater range of materials will
perform suitably in the outer ring retainer. In the outer retainer
compressive strength becomes more important and hoop strength less
important and it is possible to use ceramic materials as well as
plastic materials for this element. However, it will be apparent
that an encircling sleeve could be placed around the ring retainer
28 of the inner contacting ring without upsetting the electrical
circuitry through the connector thereby making it possible to
employ other materials.
The contacting ring and ring retainer construction is advantageous
because the stress is distributed more uniformly whereby each
portion of the structure is stressed less to achieve a total
dimensional change as its mating part is inserted in the ring.
Because the ring is first formed as a cylinder during manufacture,
the difficulty in holding its inner and outer dimensions to
tolerance is no greater than that faced in producing the prior art
connector devices which employ circular form. Consequently,
dimensional differences of the same magnitude can be expected.
The invention provides a construction in which stresses are divided
more evenly over a wider area of material and it follows, since the
total stress can be expected to be comparable, that each portion of
the connecting structure is stressed in lesser degree in the
invention thereby reducing the possibility that any part will be
deformed past its yield point. The stress being comparable, the
frictional force is comparable and the connectors are held together
such as securely in the invention as in the prior art device. It
follows also that the connecting elements in the invention can be
made to fit more tightly, thus to insure greater security for both
the mechanical and electrical connection, without danger of
overstressing the connecting parts.
* * * * *