U.S. patent number 3,858,957 [Application Number 05/392,153] was granted by the patent office on 1975-01-07 for electrical connecting members requiring lower insertion and retraction forces and providing for low contact wear.
This patent grant is currently assigned to AMP Incorporated. Invention is credited to Gilbert Douglas Ferdon, Robert George Harwood.
United States Patent |
3,858,957 |
Harwood , et al. |
January 7, 1975 |
ELECTRICAL CONNECTING MEMBERS REQUIRING LOWER INSERTION AND
RETRACTION FORCES AND PROVIDING FOR LOW CONTACT WEAR
Abstract
The improved pair of mating electrical connecting members are
incorporated into a variety of matable contacts, connectors and
other electrical devices. In one specific application, an improved
edge board connector receives an improved printed circuit board and
includes therein a plurality of contact members which are normally
biased to a disengaged position and to provide a predetermined
contact force against the mating conductor paths of the board when
it is fully engaged with the connector. The improvements include
surfaces on a free end of the contact member and on a cam bar on
the board which surfaces cooperate during engagement and
disengagement to perform a camming action to deflect the contact
member against biasing to cause it to pivot about a fixed end to
maintain a contact area on the member between the fixed and free
ends away from the board unless they are fully engaged. The camming
action is applied to the free end of the member so that the member
is less resistant to deflection than it would be if applied at the
contact area. As a result, the insertion force during engagement
and the retraction force during disengagement are lessened by the
fact that the frictional forces between the contact members and the
board are being produced by normal forces at the free end of the
member rather than by the contact force at the contact area.
Inventors: |
Harwood; Robert George
(Mechanicsburg, PA), Ferdon; Gilbert Douglas (Hummelstown,
PA) |
Assignee: |
AMP Incorporated (Harrisburg,
PA)
|
Family
ID: |
23549468 |
Appl.
No.: |
05/392,153 |
Filed: |
August 27, 1973 |
Current U.S.
Class: |
439/59; 439/267;
439/848 |
Current CPC
Class: |
H01R
12/82 (20130101) |
Current International
Class: |
H01R
12/16 (20060101); H01R 12/00 (20060101); H05k
001/07 (); H01r 013/54 (); H01r 013/62 () |
Field of
Search: |
;339/17,18,61,65,66,75,91,176,273,274,74 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Frazier; Roy D.
Assistant Examiner: Lewis; Terrell P.
Claims
What is claimed is:
1. An improved pair of mating connecting members each having
contact areas for interconnecting electrical conductors; said
members being of a type capable of being individually mounted for
engagement and disengagement along a path which is generally
parallel with the longitudinal axis of said members; at least one
of said members being normally biased to a disengaged position and
to provide a predetermined contact force at said contact areas in a
generally transverse direction when said members are engaged; said
improvement comprising:
surfaces associated with each of said members cooperating during
engagement to perform a camming action to deflect said one of said
connecting members against said biasing to cause it to pivot about
one end of said one of said members to maintain a first of said
contact areas which is on said one of said members disposed from
the other of said members until said members are substantially
fully engaged, said surfaces being aligned to maintain a second of
said contact areas which is on said other of said members away from
said one of said members until said members are substantially
engaged, said surface associated with said other of said members
being disposed along said axis of said other of said members at a
location which is more remote from said one of said members than
said second contact area so that during said engagement said one of
said members generally overlies said second contact area without
making contact therewith prior to any said deflection of said one
of said members from said disengaged position,
said camming action being applied to a region of said one of said
members which is more remote from said one end of said one of said
members than said first contact area; and
said biasing of said one of said members causing said one of said
members to be more resistent to a deflecting force applied at said
first contact area than at said region,
said one of said connecting members comprising a metallic,
electrically conductive cantilever with said biasing including
natural resilience of said cantilever against deflection and said
surface associated with said cantilever is located on its curved
extended end which includes said region,
said other of said connecting members comprising a conductor path
of a printed circuit board and said surface associated with said
conductor path is a cam bar mounted on said board and extending
transversely across said conductor path,
whereby the insertion force during engagement is lessened by
causing said deflecting force to be applied at said region rather
than at said first contact area.
2. An improved low insertion force edge connector for printed
circuit boards and the like, said boards having a plurality of
parallel spaced contact pads along at least one edge thereof and a
cam bar fixed extending transversely across said pads parallel to
but spaced from said edge, said connector comprising:
an elongated housing having an elongated circuit board receiving
aperture in one side thereof, a plurality of contact passages
extending from another side of said housing into said aperture,
a like plurality of contacts stamped and formed from electrically
conductive sheet metal, each said contact comprising a terminal
connecting portion adapted to pass through said contact passages to
mount said contacts in said housing, and an integral U-shaped yoke
portion comprising a pair of spaced apart cantilever members joined
at the base of said yoke and biased to a preset position against
deflection by the natural resilience of said metal, each said
cantilever member having a cam surface on the free end thereof
directed towards the other cantilever member and a contact surface
intermediate the length of said cantilever member also directed
towards the opposite cantilever member, said cam surfaces being
spaced apart a distance greater than in the distance between said
contact surfaces,
whereby upon insertion of a circuit board into said connector, said
board initially passes between the free cam surface ends of said
contacts without making substantially any contact therewith until
said cam surfaces subsequently engage said cam bar causing said
cantilever arms to spread apart against the inherent biasing of
said metal, said spreading causing said contact surfaces to be
spaced apart sufficiently to allow passage of said board
therebetween until said cam surfaces pass over said cam bar at
which time said cantilever arms are biased toward their preset
position with said contact surfaces engaging said pads.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an improved pair of mating connecting
members for inter-connecting electrical components and, more
specifically, to a pair of connecting members having a
configuration which makes them capable of providing a higher
contact force therebetween while decreasing the resulting wear of
their contact areas and requiring relatively low insertion force
for their engagement and retraction force for their
disengagement.
2. Description of the Prior Art
It has long been considered desirable to have a pair of mating,
multicontact connectors which provide high contact force without
producing excessive wear on the contact areas or requiring large
insertion forces. A number of zero insertion force connectors have
been offered which provide an element in addition to the basic
connecting members within the connector to increase the contact
force therebetween after insertion. The additional structure of
these connectors makes them more complicated and thus more
expensive to manufacture. In some cases, an additional manipulative
step is also required for the connection to be fully completed.
A noteworthy class of prior art devices in the printed circuit
field has provided connectors which particularly attempt to solve
the wear problem without requiring an additional manipulation of
the connectors to provide full engagement. U.S. Pat. Nos.
2,811,700; 3,140,907; 3,594,699; and 3,710,303 are in this class
and teach the utilization of camming surfaces associated with an
edge board connector and the printed circuit board which force the
biased contacts of the edge connector apart by the movement of the
board during insertion. Upon complete insertion, the biased
contacts are released to make electrical contact with the connector
paths on the board. Although some of the above-mentioned devices
include features for ease of insertion of the board, they do not
teach how to substantially reduce the insertion force of the board
into an edge board connector, or any other type of multi-contact
connector.
With the ever-increasing demand for more contacts per connector in
the printed circuit board, flatflexible cable and individually
insulated wire fields, an inexpensive, simple-to-operate, low
insertion force connector continues to be highly desirable.
Further, because of the increasing costs of gold plating, other
materials such as tin are being utilized for some contact members
causing a substantial increase in the required contact force with
the attendent insertion force problems becoming even more acute. As
a result, the above-mentioned devices each include features which
tend to unnecessarily increase the insertion force required and
thereby decrease their desirability when utilizing more contact
members and/or higher contact forces.
It, therefore, appears that the prior art does not provide a pair
of connecting members being equally applicable in conjunction with
printed circuit boards, flat-flexible cable, or individual wires
which members have a configuration for one-step engagement, are
simple and inexpensive to produce but provide a high contact force
while nevertheless insuring low wear in the contact areas and
requiring relatively low insertion force during engagement and
retraction force during disengagement.
SUMMARY OF THE INVENTION
It is, therefore, an object of the invention to provide an improved
pair of connecting members which are capable of satisfying the
requirement for high contact force while being utilized in many
types of multi-connectors in a variety of conductor fields.
A further object of the invention is to provide connecting members
of the type described which have a configuration for simple, direct
engagement that results in low wear in the contact area and
requires relatively low insertion and retraction forces as compared
with the contact force produced.
It is another object to provide connecting members of the type
described which are inexpensive, uncomplicated, and simple to
produce.
These and other objects of the invention are achieved in a
preferred embodiment thereof which is an improved pair of mating
connecting members each having contact areas for inter-connecting
electrial components and are of a type capable of being
individually mounted for engagement and disengagement along a path
which is generally parallel with the longitudinal axis of the
members. At least one of the members is normally biased to a
disengaged position and to provide a predetermined contact force at
the contact areas in a generally transverse direction when the
members are engaged.
The improvement to the members includes surfaces associated with
each member which cooperate during engagement to perform a camming
action to deflect the one connecting member against the biasing to
cause it to pivot about one end to maintain a first of the contact
areas which is on the one member away from the other member until
the members are substantially fully engaged. The camming action is
applied to a region of the one member which is more remote from the
one end than the first contact area. The biasing of the one member
causes it to be more resistant to a deflecting force applied at the
first contact area than at the region. Because of the improvements,
the insertion force during engagement is lessened by causing the
deflection force to be applied at the region rather than at the
first contact area.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a fragmentary perspective view of a preferred embodiment
of the invention with the connecting members disengaged;
FIG. 2 is a sectional side view of the embodiment of FIG. 1 as
viewed generally along line 2--2 just prior to engagement of the
members;
FIG. 3 is a view like that of FIG. 2 during engagement;
FIG. 4 is a view like that of FIG. 2 with the members engaged;
FIG. 5 is a fragmentary perspective view of an alternative
embodiment of the invention with the connecting members
disengaged;
FIG. 6 is a sectional side view of the embodiment of FIG. 5 as
viewed generally along line 6--6 just prior to engagement of the
members;
FIG. 7 is a view like that of FIG. 6 during engagement;
FIG. 8 is a view like that of FIG. 6 with the members engaged;
FIG. 9 is a perspective view of another alternative embodiment of
the invention;
FIG. 10 is a perspective view of still another alternative
embodiment;
FIG. 11 is a sectional side view of yet another alternative
embodiment of the invention prior to engagement of the members;
FIG. 12 is a view like that of FIG. 11 during engagement; and
FIG. 13 is a view like that of FIG. 11 with the members
engaged.
DETAILED DESCRIPTION OF THE EMBODIMENTS
In order to more clearly explain and understand the invention,
there are some observations and assumptions that should initially
be discussed. It should first be noted that for the class of
uncomplicated connecting members to which the improved connecting
members have now been added, the insertion force during engagement
and the retraction force during disengagement were generally found
to be directly proportioned to the contact force between the
connecting members after engagement. It is essential to recognize
that the actual minimum insertion or retraction force required is
that force which is required to overcome frictional forces between
the members during engagement or disengagement respectively. The
frictional forces between the members primarily depends upon the
static and sliding coefficients of friction, which vary with the
shapes, surface characteristics and basic materials of the members
utilized, and upon the normal forces therebetween. It is assumed
for this invention that any attempt to reduce the insertion or
retraction force which relies upon a reduction of the static and/or
sliding coefficients of friction would be equally applicable to all
the members of the subject class of connecting members. However,
the minimum normal force between all the unimproved connecting
members of the class discussed hereinabove can be found to be equal
to or greater than the contact force between the members when fully
engaged. It is, therefore, the primary concern of this invention to
disclose a concept whereby the normal force between the members
during engagement and disengagement will be substantially less than
the contact force when they are fully engaged. The resulting
reduction in frictional forces this produces will in turn reduce
the insertion and retraction force. It is with respect to these
normal forces that the description hereinbelow is primarily
directed to thereby provide a more simplified explanation of the
invention.
It should further be noted that in the preferred embodiments
discussed below, the deflectable connecting members are primarily
presented in the form of cantilevers. However, since the normal
forces resulting from the deflection on a cantilever throughout the
anticipated operational ranges of the invention are substantially
equal to those of a biased rigid beam, the later will generally be
discussed and shown to simplify the disclosure. The primary
difference between a cantilever and a rigid beam with regard to the
invention is in the specific amount of deflection of each at
various points along its length and it is felt that the disclosure
below will sufficiently explain the significance of this deflection
to enable one skilled in the art to properly practice the
invention.
Referring to the drawings, FIGS. 1 through 4 show several views of
a preferred printed circuit board 20 and edge board connector 22
which include various features of the invention. The edge board
connector 22 includes a row of connecting elements 24 rigidly
mounted therein. Only a selected number of elements 24 are shown in
FIG. 1 to simplify the figure, but any number might be included in
the connector 22 as desired without altering the basic
invention.
Each connecting element 24 is stamped and formed from electrically
conductive sheet metal and includes a pair of resiliently
deflectable connecting members 26 and an external connecting
portion 28, which in this instance is in the form of a post. The
connecting portion 28 can be selected from a large variety of
connecting means known in the art according to the particular
desired application for the connector. Further, it will later
become apparent that although being shown as having been formed
from common material, the connecting members 26 might be physically
separated and separately mounted within the connector 22 to satisfy
a particular electrical configuration without altering their basic
mechanical operation.
Each member 26 is rigidly supported within the connector 22 for
pivotal deflection about a first end 30. As shown in FIG. 2, the
member 26 is undeflected and maintained in a disengaged position,
as it extends from the first end 30, by the natural resilience of
the material from which the connecting element 24 is formed. The
natural resilience of the member 26 is such that its deflection is
opposed by a bending moment M around the end 30 which moment M
remains substantially constant throughout the anticipated
operational range of deflection of the member 26. Each member 26
further includes an extended end 32 and a contact area 34 which is
located in an intermediate portion of the member 26. Curved
portions 36 and 38 respectively at the end 32 and contact area 34
of the connecting member 26 will be discussed in detail
hereinbelow.
The circuit board 20 to be received within the connector 22
includes a plurality of conductor paths 40 and a pair of cam bars
42. Each of the conductor paths 40 is arranged to mate with a
corresponding connecting member 26 within the connector 22 with a
contact area 44 on the path 40 aligned with the contact area 34 of
the member 26. Each of the cam bars 42 is rigidly secured to its
respective side of the board 20 at a predetermined distance X from
the edge 45 of the board 22 as it extends transversely across the
conductor paths 40 in an overlying manner without disturbing their
electrical continuity. As a result of this configuration, each
connecting member 26 has a mating connecting member 46 which
includes a conductor path 40 and its corresponding portion of a cam
bar 42.
To understand how the stated objectives of the invention are
accomplished, the location of the curved portions 36 and 38 and
their significance during insertion and as shown in FIGS. 2, 3 and
4, must be examined. The curved portion 36 locates the contact area
34 on the member 26 a distance Y from the pivoted end 30 so that
the contact force Fc at the contact area 34 is equal to the moment
M divided by the distance Y. The curved portion 38 is located at
the extended end 32 to provide an interior surface 48 which is
located about a distance Z from the end 30 which distance Z is
substantially greater than Y and, in this preferred embodiment,
approximately equal to twice the distance Y. A force Fd opposing
deflection of the member 26, if the deflecting force is applied at
the surface 48, would equal the moment M divided by the distance Z.
It is, therefore, apparent that the force Fd is substantially less
than the force Fc and, in this preferred embodiment, approximately
one-half of the force Fc.
It is the purpose of the invention to provide structure to the
connecting members 26 and 46 which result in a normal force
therebetween which will equal the force Fd during engagement and
disengagement and will equal the force Fc when they are fully
engaged. As shown in FIGS. 2, 3 and 4 the alignment of the members
26 and 46 is such that the edge 45 of the printed circuit board 20
passes freely between the members 26 until a surface 50 of the cam
bar 42 makes contact with the surface 48 of the curved portion 38
of the end 32. The distance X of the board 20 is sufficiently less
than the distance between the curved portions 36 and 38, which
generally equals distance Z minus distance Y, to insure that
initial contact is made only at the surfaces 48 and 50. The
limitation on the distance X becomes apparent when it is seen that
the curved portion 36 extends into the potential path of the
circuit board 20 when the connecting members 26 are in the
disengaged position. Allowing initial contact at the surfaces 48
and 50 and then causing a deflection of the member 26 against the
force Fd by the relative movement of the cam bar 42 causes the
curved portion 36 to be deflected out of the path of the board 20
so that the force Fc is not applied to the member 46.
As the insertion causes the member 46 to approach the fully engaged
position shown in FIG. 4, the surfaces 48 and 50 cooperate to
decrease the deflection of the member 26 until the contact between
the members 26 and 46 is transferred from the surfaces 48 and 50 to
the contact areas 34 and 44. When fully engaged, the member 26 only
makes contact with the member 46 at their respective contact areas
34 and 44 with a contact force Fc therebetween. Since insertion
continues only until the members 26 and 46 are fully engaged, the
frictional forces therebetween which provide the opposition to the
insertion force are a product of the force Fd rather than the
greater force Fc which is necessary for a proper electrical
connection between the members 26 and 46.
Although FIGS. 2, 3 and 4, are described as showing the connecting
members during engagement, it can be seen that the nature and shape
of the surfaces 48 and 50 are such that the description hereinabove
for insertion is equally applicable for retraction. The retraction
force applied to the board 20 will again be opposed by the
frictional forces between the members 26 and 46. The slightest
withdrawal of the board 20 will cause the contact between the
members 26 and 46 to be transferred from the contact areas 34 and
44 to the surfaces 48 and 50. As a result, the attendant force
between the members 26 and 46 is again force Fd rather than force
Fc to produce frictional opposition during disengagement which is
generally equal to that encountered during engagement. With the
curved portion 36 again withdrawn so that it no longer makes
contact with the member 46, the retraction force is generally equal
to that which had been required for insertion.
It should also be observed from the description above that while
providing for lower insertion and retraction forces an attendant
feature of the invention is a minimization of wear at the contact
areas of the members. Providing means for shifting the normal force
between the members from the contact areas during engagement and
disengagement effectively limits the amount of surface wear at the
contact areas which might otherwise decrease the effective life of
the members.
An alternative embodiment of the invention is shown in FIGS. 5, 6,
7, and 8 in the form of an edge board connector 60 and a printed
circuit board 62. Although any number of connecting elements 64
might be utilized in the connector 60, only a selected number are
shown. Each element 64 includes a pair of connecting members 66 and
an external connecting portion 68 in the form of a crimped ferrule
in which the conductor of a wire 70 has been secured. As with
connecting elements 24, the connecting members 66 of elements 64
might be separately formed and mounted as desirable for a
particular electrical configuration.
The connecting element 64 is rigidly mounted within a base portion
72 of the connector 60 with an extended end 74 of each connecting
member 66 extending outwardly therefrom. Each connecting member 66,
like member 26 described above, is designed for biased, pivotal
deflection about a fixed end 76. However, the corresponding
extended ends 76 of each connecting element 64 rather then being
free are respectively aligned with each of a pair of commoning bars
78. Each commoning bar 78 is capable of movement to collectively
deflect each of the corresponding extended ends 74 of the members
66 from their normal disengaged position as shown in FIG. 6.
Although it should be apparent that a commoning bar could be
provided which is rigidly secured to all of the corresponding ends
74, a floating arrangement has been selected for the preferred
connector 60. To maintain the commoning bar 78 in alignment with
the ends 74 and to insure that there is no relative movement
therebetween during deflection of the member 66 by the movement of
the commoning bar 78, each of the commoning bars 78 is mounted at
its opposite ends 80 a fixed distance from the base portion 72 by
each of a pair of flexible spacers 82 extending therebetween. The
spacers 82 are designed to resist movement of the commoning bar 78
in all directions except that which is transverse to the direction
of insertion of the board 62. A guide means 84 is provided at each
end of the connector 60 which rigidly extends from the base portion
72 to protect the spacers 82 and bars 78 and to limit their
transverse travel by the notches 86 provided therein to that travel
well within the expected range of deflection of the member 66.
The printed circuit board 62 which is intended to cooperate with
the connector 60 includes a plurality of conductor paths 88
arranged so that each will be aligned with a corresponding
connecting member 66. When the board 62 is fully inserted within
the connector 60, a first contact area 90 on each member 66 makes
electrical contact with the corresponding conductor path 88 at a
second contact area 92.
To obtain the camming action required for the invention, the
commoning bars 78 are provided with cam lugs 94 and the board 62 is
provided with corresponding holes 96. Specifically, in this
embodiment, each camming surface associated with the board 62
includes the edge 98, the surface 100, and the forward edge of a
hole 96 which are all located between the conductor paths 88 of the
board 62 to prevent contact therewith during engagement. The cam
lugs 94 are located on the bars 78 in alignment with the holes 96
and the specific number of lugs 94 and holes 96 selected generally
depends upon the length of the connector 60 and the number of
elements 64 housed therein and the ability of the bars 78 to
uniformly distribute the deflection force to the connecting members
66. Although the actual normal force at each lug 94 will depend
upon the number of deflected members 66 which proportionally act
thereon, it can be adequately assumed for an analysis of the
relative effects on friction that the connecting member 66 shown in
FIGS. 6, 7 and 8 contributes its proportional share to the force at
the lug 94 when it is deflected. As a result, in the analysis
hereinbelow only this proportional share of the total force will be
discussed while recognizing that the actual frictional forces
encountered will be produced of all of the members 66 in the
connector 60.
Accordingly, it can be seen that the connecting member 66 shown in
FIGS. 6, 7 and 8 is sufficiently similar to the member 26 described
hereinabove to establish that the contact force at contact area 90
is about twice the proportional amount of force needed to deflect
the member 66 if it is applied at the lug 94. However, there are
some differing features of the members 66 and 26 which are of
significance. Unlike the extended end 38 of member 26, the cam lug
94 must extend into the path of the board 62 in order to be
properly aligned with the edge 98, the leading portion of the
camming surface associated with the board 62. It should also be
noted that the amount the lug 94 extends into the path of the board
62 when the member 66 is in the disengaged position, as seen in
FIG. 6, is greater than the extension of the contact area 90 into
the path.
When the board 62 is moved into engagement with the connector 60,
the members 66 are deflected against biasing by the camming action
of the board edge 98 acting on the lug 94. The deflection remains
substantially constant as the lug 94 is in sliding contact with the
surface 100 as shown in FIG. 7. The distance D.sub.1 between the
edge 98 and the hole 96 is greater than the distance D.sub.2
between the lug 94 and the contact area 90 so that positioning the
lug 94 at the hole 96 will cause the contact area 90 to overlie the
board 62 for alignment with the contact area 92 of the
corresponding conductor path 88. Therefore, the extension of the
contact area 90 into the path of the board 62 as compared with that
of the lug 94 when the member 66 is in the disengaged position must
be such that the area 90 is adequately withdrawn from the path
during engagement to allow contact-free overlapping of the board 62
until the lug 94 is aligned with and positioned within the hole 96.
At complete engagement, the lug 94 extends into the hole 96 without
making contact with its edges to shift the contact between the
member 66 and the board 60 to the contact areas 90 and 92 with the
attendant contact force being about twice the proportional force
applied at the lug 94 as a consequence of the deflection of the
member 66. Disengagement again deflects the member 66 by a lifting
movement on the lug 94 as a result of the camming by the forward
edge of the hole 96 to again cause the lesser force to be applied
to the board 62 and thereby limit the frictional forces in
opposition to disengagement.
Since the embodiment shown in FIGS. 5 through 8 does not include a
camming surface for the board in the form of a cam bar, there is
some contact between the member and the board in a region which
includes the conductor paths and their associated contact areas.
However, by locating the camming surface associated with the member
and the board in a common plane which is different from and not
aligned with the plane in which the respective contact areas are
located, the engagement and disengagement can be accomplished
without producing sliding contact at the contact areas which would
otherwise cause wear and thereby decrease their effectiveness.
In an effort to demonstrate the diversified application of the
invention disclosed herein, alternative embodiments are shown in
FIGS. 9 and 10 from which it can be seen that a wide variety of
configurations could be utilized to provide multi-contact
connectors providing high contact force but relatively low
insertion force. For example, the embodiment shown in FIG. 9
includes a female contact 102 and a male contact 104 which could
include any desired terminal end and could be mounted in any
suitable manner to provide for their alignment during engagement.
Female contact 102 includes a pair of resiliently deflectable
connecting members 106 similar to those found in the connector 22
and also including a contact area 108 and an extended end 110 to
provide a camming surface. The male contact 104 is a rigid member
having a pair of contact areas 112 at opposite edges of its forward
end and a pair of camming lugs 114 which act in a manner similar to
the cam bar 42 of the board 20. Providing the contacts 102 and 104
with relevant dimensions consistant with those utilized in the
embodiment shown in FIGS. 1 through 4, the camming action between
the contact 102 and 104 satisfy low insertion force requirements
during engagement and disengagement without detrimental wear at the
contact areas 108 and 112 but with a relatively high contact force
therebetween when fully engaged.
Although a two-sided configuration is shown, in FIG. 9, it should
be apparent that a multi-sided arrangement is equally applicable if
desired. A stamped and formed or machine turned socket would
provide the same function as the contact 102 by including a
plurality of members such as member 106 arranged in a side-by-side
manner to form a cylindrical receptacle while each retains the
capability of independent deflection away from the central axis.
The pin portion of the multi-sided configuration could be stamped
and formed or machine turned to a cylindrical form while having a
cross-sectional shape like that of contact 104.
Still another alternative is shown in FIG. 10 which includes
various features of the invention. Mating contact 120 and 122 are
shown in the fully engaged position and are respectively mounted in
supports 124 and 126 which are only partially shown but are
intended to include sufficient structure to maintain the contacts
120 and 122 in the desired alignment during engagement. The
terminal ends of contacts 120 and 122, not shown in FIG. 10, might
again include any desired configuration selected from the large
variety of electrical terminating means known in the art.
The contact 120 is resiliently deflectable and capable of pivotal
movement about its end 128 mounted at the support 124. A forked
extended end 130 provides a pair of spaced-apart camming surfaces
132 similar to those provided by the lugs 94 described hereinabove.
A contact area 134 is located on a curved intermediate portion 136
of the contact 120. The relevant dimensions and forces
characteristic of the member 66 above are similarly applicable for
the contact 120.
The contact 122 is a rigid member extending outwardly of the
support 126 from a U-shaped base portion 138 to a flat, extended
end portion 140 with a contact area 142 at one side thereof. The
contact has been formed to provide an intermediate portion 144
including the positive transition from the wide end portion 140 to
the narrower base portion 138 which can be received between the
camming surface 132 without making contact therewith.
Since the relevant dimensions of the contacts 120 and 122 are
similar to those of the connecting members shown in FIGS. 5 through
8, the normal force therebetween is again minimized during
engagement. However, unlike those members described above, there is
some sliding contact at the contact area 142 during engagement, but
since it is limited to the marginal edges of the extended end 140,
there is an area therebetween free from contact prior to full
engagement. This embodiment demonstrates how wiping, which is
sometimes considered desirable, can be provided. Since the normal
forces producing the wiping are less then the contact force, this
configuration would be desirable if it was felt that the amount of
wear produced by the contact force would be excessive. Further
aspects of wiping with regard to the invention will be discussed
below.
In the embodiments hereinabove, there is basically included a
resiliently deflectable member and a mating rigid member. FIGS. 11,
12 and 13 show a hermaphroditic connector 150 having mating pairs
of identical, resiliently deflectable connecting members 152 which
include the various features of the invention.
Specifically, a pair of identical connector halves 154 and 156 form
the connector 150. Each half 154 and 156 has retention means 158 by
which the connecting member 152 is supported and a cavity 160 into
which the member 152 extends. The sidewalls 162 of each half 154
and 156 include a guide means 164 so that the sidewalls 162 and
guide means 164 cooperate to insure accurate and reliable alignment
of the connector halves throughout engagement and disengagement. A
cam surface 166 adjacent the retention means 158 and projecting
into the cavity 160 will be explained below.
Each connecting member 152 is stamped and formed to include a
deflectable portion 168 and a terminal portion 170. The terminal
portion 170 is crimped or otherwise electrically and mechanically
secured to a flat-flexible cable 172 and a corresponding conductor
path therein. The terminal portion 170 is then secured to its
respective connector half 154 or 156 by the retention means 158 so
that the deflectable portion 168 extends into the cavity 160 to be
capable of pivotal deflection therein about a point 174 at its
supported end. An extended end 176 of the portion 168 is similar to
the extended end 38 described hereinabove and a contact area 178 is
located between the end 176 and the point 174. In this embodiment,
the distance X.sub.2 between the point 174 and the end 176 is about
three times the ditance Y.sub.2 between the point 174 and the
contact area 178. As a result, the deflecting force would be about
one-third the contact force to provide a correspondingly reduced
frictional opposition to engagement and disengagement.
In FIG. 11, with the connector halves 154 and 156 are partially
engaged, it can be seen the respective members 152 are in
overlapping alignment when in an undeflected position such that
continued engagement without an accompanying deflection would
result in contact therebetween in the region of the contact areas
178. However, with further engagement, as shown in FIG. 12, each
extended end 176 is cammed by the cam surface 166 of the other
connector half 154 or 156 to thereby deflect the member 152 against
the lesser normal force to withdraw the contact areas 178 and
initially prevent their mutual engagement at the higher contact
force. At full engagement, as shown in FIG. 13, the contact between
the member 152 and connector half 154 or 156 with which it mates is
shifted to the contact areas 178 at full contact force to provide
the desired electrical connection without excessive wear at the
contact areas 178 or the need for excessive force for engagement.
As in the embodiments previously presented, the advantages found
during engagement are also present during disengagement.
While there has been shown and described various preferred
embodiments of the invention, it will be obvious to those skilled
in the art that changes and modifications may be made therein
without departing from the claimed invention. For example, if it
were felt desirable to alter the connection to resist rather then
assist disengagement for a particular application, the coefficient
of friction could be increased by altering the slope or character
of the surfaces during disengagement to thereby increase the
friction in opposition to the disengagement.
If, for another example, wiping of the contact area is felt
essential but wear is not considered a problem, continued movement
in the direction of engagement after full engagement on any of the
embodiments above would wipe the contact areas. The small amount of
travel necessary for this wiping could make the method acceptable
even though the contact force would be present during the
wiping.
If wear is considered a problem, the embodiment shown in FIG. 10
demonstrates how wiping could be obtained at a reduced normal
force. If the reduced normal force would still cause too much wear,
it would be possible to align the extended end of a cantilever
member for sliding contact with the contact area of the rigid
member at a deflection substantially less than the anticipated
operational range utilized in the preferred embodiments. This
reduced deflection of a cantilever would be at a normal force
substantially less than any force previously discussed. During the
engagement, the extended end would wipe the contact area of the
rigid member at the lesser normal force and then a properly
designed camming surface associated with the rigid member could
further deflect the cantilever member in manner described
hereinabove to allow the engagement while reducing the resistance
to insertion.
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