U.S. patent number RE28,595 [Application Number 05/305,132] was granted by the patent office on 1975-10-28 for current control apparatus and methods of manufacture.
This patent grant is currently assigned to Essex International, Inc.. Invention is credited to Gideon A. DuRocher.
United States Patent |
RE28,595 |
DuRocher |
October 28, 1975 |
**Please see images for:
( Certificate of Correction ) ** |
Current control apparatus and methods of manufacture
Abstract
Current control apparatus operable to function selectively as a
conductor, a circuit breaker, or a thermostat comprises a body
formed of electrically insulating, compressible, inorganic,
preferably elastomeric material having one or more portions thereof
provided with discrete, electrically conductive particles which
move relatively to one another into and out of engagement in
response to changes in the state of compression to which the body
is subjected or in response to variations in temperature of the
body. The conductive portion or portions of the body extend through
the latter from one side to the other, but are electrically
isolated from one another by the nonconductive body portions. The
body may include upstanding ribs or flanges on either or both of
its opposite surfaces for the purpose of providing seals to prevent
the entry of moisture or other foreign matter to the area bounded
by the flanges.
Inventors: |
DuRocher; Gideon A. (Mount
Clemens, MI) |
Assignee: |
Essex International, Inc. (Fort
Wayne, IN)
|
Family
ID: |
26710818 |
Appl.
No.: |
05/305,132 |
Filed: |
November 9, 1972 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
034320 |
May 4, 1970 |
03648002 |
Mar 7, 1972 |
|
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Current U.S.
Class: |
200/265; 200/511;
968/881; 439/77; 439/638; 200/85R; 338/114; 439/587; 439/592 |
Current CPC
Class: |
H01C
10/106 (20130101); H01R 13/2414 (20130101); H01R
13/02 (20130101); H01H 1/029 (20130101); G04G
17/06 (20130101) |
Current International
Class: |
H01H
1/029 (20060101); G04G 17/06 (20060101); H01C
10/00 (20060101); H01C 10/10 (20060101); H01R
13/02 (20060101); H01H 1/02 (20060101); G04G
17/00 (20060101); H01R 13/24 (20060101); H01R
13/22 (20060101); H01H 003/00 (); H01R
013/24 () |
Field of
Search: |
;339/17R,17E,17A,17C,17M,18R,18C,59R,59M,61R,61M,15R,15T,151R
;174/68.5 ;29/625,628 ;200/265 ;338/114 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Frazier; Roy D.
Assistant Examiner: Staab; Lawrence
Attorney, Agent or Firm: Learman & McCulloch
Claims
I claim:
1. Current control apparatus comprises a body formed of
electrically nonconductive, resiliently compressible material, said
body having at least one opening extending therethrough; and at
least one composite pad occupying said opening and adhered to said
body, said pad being formed of resiliently compressible,
electrically nonconductive material having discrete, electrically
conductive particles dispersed therethrough, said particles being
responsive to compression of said pad to establish an electrically
conductive path through said pad, said pad being exposed at
opposite sides of said body for engagement with conductors.
2. The apparatus set forth in claim 1 wherein the resilience of
said material of said pad is such as to disable said particles from
establishing said conductive path except when said material of said
pad is compressed.
3. The apparatus set forth in claim 1 wherein said material of said
pad has a thermal coefficient of expansion different from the
thermal coefficient of expansion of said particles whereby said
material and said particles expand and contract at different rates
in response to changes in temperature.
4. The apparatus as set forth in claim 1 wherein the nonconductive
material of said pad is the same as the material of said body.
5. The apparatus set forth in claim 1 wherein said body has an
upstanding, deformable endless flange at least at one side thereof
and encircling said pad.
6. The apparatus set forth in claim 1 wherein said body has an
upstanding, deformable endless flange on each of its said two
opposite sides and encircling said pad.
7. The apparatus set forth in claim 1 wherein said body has a
plurality of spaced-apart openings therethrough and in each of
which is adhered one of said pads, each of said openings being
solated from one another by the material forming said body.
8. The apparatus set forth in claim 7 wherein said pads are solated
from one another by upstanding resilient ribs.
9. The apparatus set forth in claim 7 wherein the height of each of
said pads is at least as great as the thickness of said body.
10. The apparatus set forth in claim 1 including an upstanding
deformable endless rib at least at one side of said body and
encircling all of said pads.
11. The apparatus set forth in claim 10 including additional ribs
upstanding at said one side of said body and cooperating with the
first-mentioned rib to encircle each of said pads.
12. The apparatus set forth in claim 7 including an upstanding,
deformable, endless rib on both sides of said body, each of said
ribs encircling all of said pads.
13. The apparatus set forth in claim 1 wherein said body is
quadrangular.
14. The apparatus set forth in claim 1 wherein said body is
circular.
15. The apparatus set forth in claim 1 wherein said body is
annular.
16. The apparatus set forth in claim 1 including a conductor in
engagement with said pad; and means for pressing said conductor
against said pad with sufficient force to render said pad
electrically conductive.
17. The apparatus set forth in claim 16 wherein said pressing means
comprises a pair of members sandwiching said body therebetween; and
means for clamping said members to one another under sufficient
force to cause said conductor to compress said pad.
18. The apparatus set forth in claim 17 wherein said clamping means
includes a spring.
19. The apparatus set forth in claim 16 wherein said conductor
constitutes part of a printed circuit.
20. The apparatus set forth in claim 18 wherein said printed
circuit is flexible.
21. The apparatus set forth in claim 1 wherein said pad has an
inherent compression such as to render it conductive without the
application of external compressive force.
22. The apparatus set forth in claim 1 wherein the coefficient of
thermal expansion of the nonconductive material of said pad is
greater than the thermal coefficient of expansion of said
conductive particles.
23. A method of forming current control apparatus comprising
molding a nonconductive material into a form-stable, resilient body
having at least one opening therethrough; and occupying said
opening with a molded form-stable composite substance adhered to
said body and comprising nonconductive material having conductive
particles dispersed therethrough.
24. The method set forth in claim 23 wherein said opening is formed
during the molding of said body.
25. The method set forth in claim 23 wherein said opening is formed
following the molding of said body.
26. The method set forth in claim 23 wherein said composite
substance is molded under pressure sufficient to maintain said
particles in engagement one with another.
27. The method set forth in claim 23 wherein said composite
substance is molded under pressure insufficient to maintain said
particles in engagement with one another in the absence of the
application of an external compressive force on said substance.
28. The method set forth in claim 23 wherein the nonconductive
material of said body is the same as the nonconductive material of
said composite substance.
29. The method set forth in claim 23 wherein said composite
substance is molded in place in said opening.
30. The method set forth in claim 23 including providing an
upstanding endless rib at least at one side of said body and
encircling said opening.
31. The method set forth in claim 23 including providing an
upstanding endless rib at opposite sides of said body and
encircling said opening at the opposite ends thereof. .Iadd. 32.
Current control apparatus comprising a body formed of electrically
non-conductive, resiliently compressible material, said body having
at least one opening extending therethrough; and at least one
composite pad fitted into said opening, said pad being formed of
resiliently compressible, electrically non-conductive material
having discrete, electrically conductive particles dispersed
therethrough, said particles being responsive to compression of
said pad to establish an electrically conductive path through said
pad, said pad being exposed at opposite sides of said body for
engagement with conductors. .Iaddend..Iadd. 33. A method of forming
current control apparatus comprising molding a non-conductive
material into a formstable, resilient body having at least one
opening therethrough; and fitting into said opening a molded,
formstable, composite substance comprising non-conductive material
having conductive particles dispersed therethrough. .Iaddend..Iadd.
34. Electrical interconnecting apparatus comprising a dielectric
material having first and second opposite surface areas and having
at least one hole extending through the dielectric material from
the first surface area to the second surface area, at least one
elastomeric compressible resilient electroconductive element
disposed in the hole, the at least one element comprising a
dielectric resin containing discrete electrical conductors held in
electrical conducting relationship in the element. .Iaddend..Iadd.
35. The electrical interconnecting apparatus of claim 34 wherein
the dielectric material has a plurality of holes therein and
wherein the at least one element comprises a plurality of elements
disposed within the holes for electrically connecting a plurality
of first contacts adjacent the first surface area of the material
with a plurality of second contacts adjacent the second surface
area of the material. .Iaddend..Iadd. 36. The electrical
interconnecting apparatus of claim 34 wherein the dielectric
material comprises a resin. .Iaddend..Iadd. 37. The electrical
interconnecting apparatus of claim 34 wherein the dielectric
material comprises a flexible, thin resin sheet. .Iaddend..Iadd.
38. The electrical interconnecting apparatus of claim 34 wherein
the dielectric material comprises a thin resilient resin sheet.
.Iaddend..Iadd. 39. The electrical interconnecting apparatus of
claim 34 wherein the dielectric material comprises a flexible
resilient and compressible resin sheet having first and second
opposite faces and having a plurality of holes extending through
the sheet, and wherein the at least one electroconductive elements
comprises a plurality of elastomeric rods disposed in the holes,
the rods having electroconductors therein whereby a plurality of
contacts adjacent the first face are electrically connected with a
plurality of contacts adjacent the second face. .Iaddend..Iadd. 40.
The electrical connecting apparatus of claim 39 wherein each rod
has a plurality of relatively small discreet conductors held by the
elastomeric rods in electrical conducting relation which is
enhanced by compressing the rods between contacts adjacent the
sheet faces. .Iaddend..Iadd. 41. The electrical interconnecting
apparatus of claim 34 further comprising first contact bearing
means adjacent the first surface area and having positioned thereon
at least one first contact ajdacent the at least one element, and
second contact holding means adjacent the second surface area and
having a second contact adjacent the at least one element and means
pressing the first and second contact means inward thereby tending
to compress the at least one element and completing an electrical
circuit between the first and second contacts. .Iaddend..Iadd. 42.
The apparatus of claim 34 wherein the element extends from one
surface of the dielectric material to an opposite surface thereof.
.Iaddend..Iadd. 43. The method of joining electrical contacts
comprising positioning contacts opposite each other, interposing a
dielectric retainer having a conductive elastomeric element
extending therethrough between the contacts and pressing the
contacts towards each other, thereby compressing the conductive
elastomeric element and completing a circuit between the
contacts..Iaddend.
Description
The invention disclosed herein relates to apparatus and the
manufacture of such apparatus for controlling electric circuits and
more particularly to a control device comprising a body formed of
electrically insulating, compressible, preferably elastomeric
material provided with one or more electrically isolated portions
each of which has electrically conductive particles dispersed
therethrough which are operable to move into and out of
electrically conductive relationship in response to changes in the
state of compression of the body or in response to changes in
temperature to which the body is subjected. More particularly, the
invention relates to a resilient body having portions thereof
constituted by a mixture of rubbery, insulating material and
electrically conductive particles which portions are adapted to be
rendered conductive or nonconductive according to changes in
pressure or temperature to which such portions are subjected. The
body may be formed to any desired shape and may be provided with
upstanding flanges or ribs of deformable material, thereby enabling
the electrically conductive portions to be sealed against
contamination by moisture or other foreign agents. Apparatus
constructed according to the invention is especially useful in
establishing electrical continuity between either rigid or flexible
printed circuits, between wires and printed circuit conductors, and
between conventional terminals of the kind found in circuit connect
and disconnect devices, but the apparatus equally well is adapted
for use in circuit breakers and thermostats.
An object of this invention is to provide current control apparatus
which selectively may be either normally conductive or normally
nonconductive and which is convertible from one condition to the
other in response to changes in pressure or temperature.
Another object of the invention is to provide current control
apparatus having one or more electrically conductive portions
forming a unitary part of a body and in which each conductive
portion is isolated by nonconductive material.
Another object of the invention is to provide current control
apparatus having a resilient body formed of compressible,
nonconductive material and which is provided with electrically
conductive portions isolated from one another by the nonconductive
material, the including self-contained sealing means for protecting
the conductive portions against contamination.
A further object of the invention is to provide methods of
manufacturing apparatus of the kind described.
Other objects and advantages of the invention will be pointed out
specifically or will become apparent from the following description
when it is considered in conjunction with the appended claims and
the accompanying drawings in which:
FIG. 1 is an isometric view of a control device constructed
according to one embodiment of the;
FIG. 2 is an isometric view, partly broken away, of another
embodiment of a control device;
FIG. 3 is a view partly in top plan and partly in section of a
connector in which either of the devices shown in FIGS. 1 and 2 may
be used;
FIG. 4 is a sectional view taken on line 4--4 of FIG. 3;
FIG. 5 is an elevational view of the conductor;
FIG. 6 is an isometric view of another embodiment of control
device;
FIG. 7 is a sectional view taken on the line 7--7 of FIG. 6.
FIG. 8 is a view similar to FIG. 2, but illustrating still another
embodiment of control device;
FIG. 9 is a sectional view illustrating a typical control device
used as an interface between a printed circuit and wire
conductors;
FIG. 10 is a sectional view taken on the line 10--10 of FIG. 9;
FIG. 11 is a view similar to FIG. 9 but illustrating the control
device sandwiched between two printed circuits;
FIG. 12 is a view similar to FIG. 8, but illustrating another
embodiment of control device;
FIG. 13 is a view similar to FIG. 9, but illustrating the device of
FIG. 12 used with a double-deck printed circuit;
FIG. 14 is an isometric view of another embodiment of control
device; and
FIG. 15 is a sectional view taken on the line 15--15 of FIG.
14.
A control device constructed in accordance with the invention
comprises essentially a unitary body or pad formed of a synthetic,
inorganic, resilient, nonconductive substance such as silicone
rubber or polyurethane, body having at least one inlay or portion
thereof constituted by nonconductive material such as silicone
rubber or polyurethane throughout which is dispersed a quantity of
discrete, electrically conductive particles. According to one
embodiment of the invention the portion of the pad containing the
conductive particles and the dispersion of the particles are such
that, when the pad is in its normal, unstressed condition the
electrical resistance of the pad is infinite and the pad is
nonconductive. When the pad is subjected to compressive force of
sufficient magnitude, however, the particles are forced to move
relatively to one another into particle-to-particle engagement. The
resistance of the pad thereupon changes to that of the metal
particles and the pad becomes electrically conductive. Upon release
of the compressive force, the inherent resilience of pad restores
it to its normal, unstressed condition whereupon the particles
again move relatively to one another, but in this instance in such
manner as to disengage one another and render the pad
nonconductive. The change from conductive to nonconductive
condition, and vice versa, occurs rapidly, as is the case with a
conventional switch of the snap-action type.
According to another embodiment of the invention the portion of the
pad containing the conductive particles is molded under pressure so
that when the pad is in its normal, unstressed condition the
conductive particles are in conductive engagement, thereby
rendering that portion of the pad electrically conductive without
the application of an external compressive force. The nonconductive
material has a coefficient of thermal expansion which is
substantially greater than that of the metal particles so that,
when the temperature of the pad is raised, either by current flow
or by an increase in ambient temperature, the nonconductive
material expands at a greater rate than that of the conductive
particles so as to cause the particles to move apart and render the
pad nonconductive. Upon cooling of the pad, the thermally expanded
material will contract, thereby inherently returning the conductive
particles into conductive engagement.
The number of particles which move into particle-to-particle
engagement may vary according to the force applied to the body or
to the compressive force under which it is formed, and it is not
essential that all of the particles engage one another. It is only
necessary that a train of particles be in engagement between the
other current conductors of a circuit so as to establish a
conductive path through the body. In fact, it is preferred that not
all of the particles in the body engage one another. In such a
case, one train of engaged particles may be consumed by an overload
current, thereby rendering the body nonconductive. Other particles,
however, will be unaffected thereby making it possible for such
other particles to form additional trains for current
conduction.
An advantage of devices of the kind herein disclosed is the ease
with which they may be varied to conform to differing operating
requirements. In general, the compressive force required to render
a composite body portion conductive will be directly proportional
to the thickness of the pad. A given sample of the composite body
or pad, therefore, can be made responsive to extremely light
pressures or responsive to relatively heavy pressures, depending on
the thickness of the pad. The sensitivity of the device also is
related to the quantity and size of the conductive particles. The
force required to render a pad conductive varies, in general,
inversely according to the quantity of particles contained within
the pad and varies directly according to the size of such
particles. It is possible, therefore, to manufacture devices having
greatly differing operating characteristics.
The force required to render a composite body portion conductive,
and the amount of travel necessary to effect compression of the
body portion to a state of conductivity also is related to the
density of the body. Thus, a relatively dense body requires the
application of a greater compressive force than does a less dense
or foamed body, whereas the foamed body requires a greater
compressive movement than does the more dense body. Consequently,
the force and stroke of an operating mechanism can vary within wide
limits.
The material from which the device is made should be resilient at
both low and high temperatures, readily moldable, stable at high
temperatures, porous or nonporous, resistant to ozone, oil and
arcing, inorganic semiinorganic durable, low in carbon content, and
have high dielectric strength. Certain kinds of polyurethanes and
silicone rubbers possess all of these properties. Silicone rubbers
are prepared by milling together a dimethyl silicone polymer, an
inorganic filler, and a vulcanizer or catalyst. Many different
fillers may be used, such as titania, zinc oxide, iron oxide,
silica, and the like. The type and amount of filler used alters the
chemical, physical, and electrical properties. It is possible,
therefore, to produce many different kinds of silicone rubbers
which have the properties referred to above.
Many varities of silicone rubbers exist which perform
satisfactorily. For example, good results have been obtained with
silicone rubbers formed by combining resins 850 or 3120 (Dow
Corning Corporation, Midland, Michigan) with the manufacturer's
recommended S, F or H catalyst or vulcanizer which includes as its
active ingredients such compounds as dibutyl tin dilorate or stanis
octoate. Satisfactory results also have been obtained with silicone
rubbers formed by combining RTV-7 resin (General Electric Company,
Schenectady, New York) with the manufacturer's Nuocure 28
vulcanizer. Metallic particles are stirred into the resin-catalyst
substances in sufficient quantity to be dispersed substantially
uniformly throughout the mass. The mixture then is poured into a
mold and cured in the manner prescribed for the particular resin.
Polyurethane devices are made in the same way, but utilizing the
appropriate resins and catalysts. The mold may be any desired shape
to produce a composite solid or foamed body composed of the
elastomeric material and the metal particles, the latter being
dispersed throughout the body, including its outer surfaces.
The metal particles should be formed of a metal that has excellent
conductive properties and also should be one which, if it oxidizes,
has an electrically conductive oxide. Particles made from noble
metals such as silver and gold have the desired inherent
conductivity and normally form conductive oxides, but particles
composed entirely of noble metal are quite expensive. It is
preferred, therefore, to use discrete, spherical metal particles
composed of base metals such as copper, iron and the like, coated
with silver and which act very much like solid silver particles,
but which are less expensive. The size of the particles, may vary
from 0.05 mil to 100 mils. Excellent results have been obtained
utilizing particles in the 3-8 mils range. The size of the
particles should vary according to the thickness of the body or
pad, the amount of force desired to be exerted on the body, and the
value of the current desired to be passed through the body. In
general, the current which can be accommodated by a body is
directly proportional to the size of the metal particles.
A typical molded body may have its nonconductive portion formed of
silicone resin and catalyst in the ratio of 10 to 1 by weight and
its conductive portion or portions formed of the same resin and
catalyst, in the same weight ratio, but having a particle to
silicone ratio of 6 to 1. The overall body may be of any desired
area and of any desired thickness, such as 0.060 inch. It should be
apparent, however, that the ratios and dimensions recited may be
varied within rather wide limits depending on the particular
characteristics the resulting body are to possess. When a sample of
the conductive portion of a typical body is viewed under a
microscope, the silicone rubber appears to encapsulate each
metallic particle and isolate it from the others, but the rubber
does not prevent relative movement of the particles. When the body
is subjected to compressive forces and deformed or compressed, the
metallic particles are forced to move relatively to one another and
to the encapsulating rubber in such manner that a sufficient number
of the particles move into engagement with one another to establish
a conductive train or path through the body portion. Current then
may flow through the conductive body portion. The low shear
resistance of silicone rubber and the nonadherence of the rubber to
the particles facilitate the movement of the particles. The
resistance of the conductive body portion, when conductive,
corresponds substantially to the resistance of the metal particles.
Since the electrical resistance of noble metals, such as silver, is
quite low, the resistance of the conductive portion also is quite
low and, therefore, permits the latter to accommodate a high value
current. For example, a conductive pad constructed of Dow Corning
3120 silicone rubber and containing 3-mil, silver coated copper
particles in the ratio referred to above and having a thickness of
0.06 inch was sandwiched between conventional terminals and was
capable of conducting a current of 50 amperes without impairment.
Another, similar pad was incorporated in a 115-volt AC circuit
including a 25-watt electric lamp bulb and was cycled at the rate
of 130 cycles per minute. After more than 7 million cycles of
operation, the pad still functioned perfectly.
It is believed that, when a conductive path is established through
the conductive body portion, the current density of such path
between the other circuit components is much less than that of the
point-to-point contact of conventional metal-to-metal connectors.
The resistance of the body portion, when conductive, has been
measured to be 0.0025 ohms which is equivalent to the resistance of
4.7 inches of 18 gauge wire or 3 inches of 20 gauge wire.
When the compressive force applied to the conductive body portion
is released, the inherent resilience of the silicone rubber causes
the latter to expand and assume its normal, unstressed condition,
whereupon the engaged conductive particles are forced to move out
of engagement, thereby disestablishing or breaking the conductive
path. If there should be any arcing between particles as they
separate from one another, the arcing will be confined to the
interior of the body. Even though the presence of an arc may
destroy or impair the current conductive capacity of the particles
between which the arc forms, there are so many particles in the
body and, consequently, so many possible current conductive paths,
that a potential path always exists through the body throughout its
life expectancy. The presence of arcs within the body leaves a
track, but because of the low carbon content of the silicone rubber
the arcing track is composed of nonconductive inorganic matter,
rather than a conductive carbon track such as would be left in
organic materials.
Apparatus constructed in accordance with the embodiment of the
invention illustrated in FIG. 1 comprises a body 1 formed of
compressible, resilient, nonconductive, elastomeric material such
as silicone rubber and which may be annular as shown or, if
preferred, the body may comprise a disc. The body 1 may be formed
by mixing a silicone resin with a suitable catalyst in a known
manner and introducing the mixture to a mold. The mold preferably
has a plurality of spaced apart ribs so taht the body 1, when
formed, will have a corresponding plurality of windows or openings
2 spaced around a central opening 3. Alternatively, the body 1 may
be molded as a solid disc and the openings 2 and 3 formed in the
body following curing of the latter. When the body 1 has been
cured, the openings 2 may be filled with a mixture of silicone
rubber like that from which the body is formed, but having
dispersed therethrough a plurality of electrically conductive
particles of the kind hereinbefore mentioned. Each of the openings
2 thus will form a mold for a pad or portion 4 which may be
rendered selectively conductive or nonconductive as will be pointed
out in more detail hereinafter. The portion 4 will bond itself to
the body 1.
FIG. 2 illustrates an annular body 5 similar to the body 1 having
conductive pads or portions 6 identical to the conductive portions
4 and spaced angularly about a central opening 7. The only
difference between the bodies 1 and 5 is that the body 5 has
upstanding flanges or ribs 8 and 9 at its inner and outer
peripheries, respectively, which are molded integrally with the
nonconductive portions of body 5. It will be understood that,
although the flanges are illustrated as projecting beyond both
surfaces of the body 5, the flanges could be formed in such manner
as to extend beyond one surface only of the body.
The body 10 illustrated in FIG. 6 is like the body 1, but is
quadrangular and is flat on both surfaces. In the manufacture of
the body 10 openings 11 are formed which subsequently are filled
with material 12 constituting a mixture of the insulating material
from which the body 10 is formed and electrically conductive
particles of the kind hereinbefore described.
The body 13 illustrated in FIG. 8 is similar to the body 10 in that
it is rectangular and has spaced apart openings 11 filled with a
material 12 comprising a mixture of the insulating material and
conductive particles. The body 13 differs from the body 10 in that
the body 13 has an upstanding marginal rib or flange 16 extending
from either or both surfaces of the body 13.
FIG. 12 discloses a rectangular body 17 formed of insulating
material like that described earlier and having a marginal rib or
flange 18 which projects beyond either or both surfaces of the
body. In the formation of the body 17, a plurality of aligned,
spaced-apart pairs of preferably cylindrical openings 19 are
provided, which openings subsequently are filled with the mixture
of insulating material and conductive particles.
The body 20 illustrated in FIG. 14 is in the form of a disc and has
a plurality of spaced-apart openings 21 containing the mixture of
insulating material and conductive particles. The body 20 may have
upstanding, peripheral ribs 22 and 24 and similar radial ribs 23
which isolate the conductive portions 21 from one another. The ribs
22, 23 and 24 may project from either or both surfaces of the body
20.
The several bodies disclosed herein can be used in conjunction with
a large number of different kinds of electrical circuits and in
conjunction with a large number of different kinds of coupling or
connecting devices. One of such coupling devices is designated
generally by the reference character 27 in FIGS. 3-5 and comprises
a socket member 28 formed of insulating material having a
cylindrical skirt 29 which defines an internal chamber 30 having a
flat base 31. The member 28 has a central opening 32 around which
is located a plurality of uniformly spaced, electrically conductive
terminals 33, the inner ends of which preferably are flat and
project slightly beyond the base 31 into the chamber 30.
The connector 27 also includes a carrier member 34 formed of
insulating material having a plurality of terminals 35
corresponding to the number and spacing of the terminals 33, the
inner ends of the terminals 35 also projecting slightly beyond the
carrier 34. The carrier 34 is adapted to be fitted removably into
the chamber 30, the carrier having a tongue 35 which may be
accommodated in a groove 36 formed in the skirt 29 so as to assure
alignment of the terminals 33 and 35.
The connector 27 includes means 37 for separably coupling the
members 28 and 34 to another. The coupling means comprises a shaft
38 slidably mounted in the carrier 34 and adapted to extend through
the opening 32 in the member 28. At one end the shaft 38 terminates
in a finger piece 39 and at its other end is provided with a pair
of transversely projecting arms 40 which are adapted to be received
in seats 41 provided in the member 28. The opening 32 is of such
size as to pass the arms 40 and the seats 41 are formed in blocks
42 that are spaced from one another by slots 43 so as to permit
relative rotation of the shaft 38 and the member 28 and
corresponding movement of the arms 40 from the slots 42a to the
seats 41. The connector members 28 and 34 are biased toward one
another by a spring 43 which acts between the finger piece 39 and
the carrier 34. The spring thus urges the terminals 33 and 35
toward one another when the members 28 and 34 are assembled.
Either of the current control bodies 1 or 5 may be used in
conjunction with the coupling member 27. For purposes of
illustration, the body 5 is shown in FIG. 4 and is interposed
between the members 28 and 34 in such manner that the conductive
portions 6 are sandwiched between the pairs of terminals 33 and 35.
In these positions of the parts, the spring 43 causes the
confronting terminals 33 and 35 to compress the conductive portions
6 of the body 5 with such force as to establish a conductive path
between the confronting terminals via the conductive particles
contained in the material 6. Each of the conductive portions,
however, is isolated electrically from one another by the
intervening insulating portion of the body 5.
Of particular significance is the ability of the conductive
portions 6 to establish a current path between a pair of terminals
33 and 35 even though the latter are not in perfect alignment. In
fact, misalignment to a considerable extent may be tolerated
without degradation of the electrical conductivity between pairs of
terminals.
When the body 5 is in the condition shown in FIG. 4, the flanges 8
and 9 also are compressed between the body members 28 and 34,
thereby effecting a seal which completely surrounds the terminals
33 and 35 so as to shield the latter and the conductive portions 6
against contamination by moisture or other foreign matter.
The apparatus shown in FIG. 9 comprises either a flexible or rigid
printed circuit having a substrate 45 formed of insulating material
and on the upper surface of which is a plurality of conductive
strips 46 of the kind commonly found in printed circuits. Mounted
atop the substrate 45 is the current control body 13, although the
body 10 could be used equally well. The body 13 is so arranged that
the conductive portions 12 lie atop exposed portions of the
conductive strips 46. Atop the body 13 is a nonconductive carrier
47 provided with a plurality of rigid wire terminals 48 which
extend through the carrier 47 so as to be engageable with the
material 12 when the parts are assembled. The members 45 and 47 may
be joined by screws 49 or the like so as to subject the body 13 to
compression, the terminals 48 effecting sufficient compression of
the portions 12 to render such portions conductive and thereby
enable current to pass from the conductors 46 to the conductors 48.
Each portion 12 of the body 13 is isolated from one another by the
nonconductive material constituting the remaining portions of body
13. The flange 16 effects a seal around the entire body 13 so as to
prevent the introduction of moisture or other foreign matter to the
area of the printed circuit occupied by the body 13.
The apparatus shown in FIG. 11 is similar to the apparatus shown in
FIG. 9, but differs from the latter in that the body 13 is
sandwiched between a pair of flexible printed circuit members each
of which includes a nonconductive substrate 50 and conductive
strips 51. Suitable backing members 52 are associated with the
printed circuit members and are maintained in assembled relation by
means of screws 53 or the like and which subject the body 13 to
sufficient compression as to render the portions 12 conductive,
thereby permitting current to be conducted between the confronting
conductors 51 of the two printed circuit members.
FIG. 13 illustrates, in great exaggeration, a double-deck printed
circuit assembly or unit 55 comprising one or more conductive
strips 56 sandwiched between insulating layers 57 and 58 and other
conductive strips 59 sandwiched between the layer 58 and a similar
nonconductive layer 60. The strips 56 and 59 may overlie one
another or otherwise be arranged in any desired manner. At one end
of the unit 55 the insulating layer 57 is cut away to expose the
conductive strips 56 and the layer 58 is cut away to expose the
conductive strips 59. If the strips 56 and 59 overlie one another,
as shown, the exposed portions of the strips are staggered.
Atop the unit 55 is placed the current control body 17 in such
manner that one portion 19 of a pair of such portions overlies the
exposed conductor 56 and the other portion 19 of the pair of
portions overlies the exposed conductor 59. A carrier 61 provided
with pairs of terminals 62 spaced apart according to the spacing of
the portions 19 then is placed over the body 17, so that the
terminals 62 of a pair thereof bear against the two corresponding
portions 19. The carrier 61 is assembled with the unit 55 by means
of a backing plate 63 and screws 64 which maintain the body 17
under such compression as to render the portions 19 conductive. The
flange 18 seals the body 17 between the members 61 and 63 and
against the unit 55 so as to prevent the entry of moisture and
other foreign matter between the body 17 and the respective
conductors.
The terminals 62, although shown as fixed elements, could
constitute depressable contacts of a switch in which case the body
55 would not normally be compressed to the degree required to
render the portions 19 conductive. Such portions could be rendered
conductive, however, by depression of a contact 62 and consequent
compression of the associated portion 19. The same observation
applies equally to all of the other disclosed embodiments.
Apparatus constructed according to the invention, therefore, lends
itself admirably to on-circuit switch mechanisms associated with
printed circuits.
In the preparation of any of the body members herein disclosed the
current control portions thereof may be normally nonconductive or
normally conductive. Whether the body members have normally
conductive or normally nonconductive portions will depend upon
several factors such as the thickness of the body, the
concentration of the conductive particles, the size of the
conductive particles, and whether or not the conductive portions
are molded under pressure or are molded without being subjected to
compressive forces. If a particular body has its conductive portion
or portions molded under pressure in such manner as normally to be
conductive, then the application of external pressure on the body
is not required. On the other hand, if the conductive portion of a
body is molded in such manner as normally to be nonconductive, then
external pressure must be applied on that portion to render it
conductive.
Whether or not some portion of a body is normally conductive or
normally nonconductive will depend upon the use to which the body
is to be put. For example, the apparatus 27 may have the
characteristics of either a manually or automatically resettable
circuit breaker. In such a case, it is preferred that the
conductive particles of the portions 6 normally be disengaged,
thereby necessitating compression of such portions by means of the
spring to render them conductive. In the compression of the
portions 6, the normally disengaged conductive particles will be
moved relatively to one another so as to establish at least one
train of engaged particles through the portions 6, thereby
establishing a conductive path between the confronting terminals 33
and 35. Should an excessive current then be passed through the
portions 6, the engaged particles constituting the current path
will be heated, and possibly consumed, thereby breaking the circuit
continuity between the confronting terminals 33 and 35.
The excessive current and the consumption of the engaged particles
will generate a certain amount of heat which will be absorbed by
the insulating material in which the conductive particles are
contained. If the material has a coefficient of thermal expansion
greater than that of the conductive particles, as is the case with
silicone rubber and silver coated, copper particles, the heat
generated by the excessive current will cause the nonconductive
material to expand, as is permitted by the spring 43, thereby
effecting disengagement of the particles. If the spring force under
which the portions 6 are compressed is relatively light, the
contraction of the portions 6 during cooling will not be sufficient
to reestablish a conductive path through the portions 6. The
portions 6 may be rendered conductive again by applying compressive
force on the coupling members 28 and 34 manually. However, the
force of the spring 43 may be such as to assure compression of the
portions 6 following their cooling by an amount such as to force
other conductive particles into engagement and reestablish
electrical continuity through the portions 6. Thus, the apparatus
may constitute either a manually resettable or an automatically
resettable circuit breaker.
When a body member is adapted to function as a thermostat, the
conductive portion or portions thereof will be formed under
sufficient pressure as normally to be conductive. When the
temperature of the body is raised, either by heat generated by an
electric current or by an increase in ambient temperature, the
thermal expansion of the nonconductive material will effect
separation of the conductive particles so as to render the body
nonconductive. When the body cools, however, it will contract
whereupon the conductive particles again will be engaged with one
another so as to reestablish circuit continuity through the
body.
The ability of any of the several composite bodies disclosed herein
to serve as an interface between rigid terminals of a coupling,
between rigid terminals and either rigid or flexible printed
circuits, and between printed circuits themselves enables a great
many production and assembly problems associated with switchgear to
be solved. For example, the coupling device 27 can be used in lieu
of pin and socket type couplers, thereby avoiding the problems
associated with alignment of the pins with the sockets. Moreover, a
body such as the body 13 can be interposed between two parts an
assembly intended to be fastened together and carrying conductors
which must be joined to one another. In such a case the conductive
portions of the body may be aligned within reasonable limits with
the other conductors, whereupon fastening of parts of the assembly
automatically will effect compression of the conductive body
portions and establish circuit continuity. In effect, therefore,
the body enables parts of an assembly to be self-wiring upon their
being fitted together.
The apparatus and methods disclosed are representative of presently
preferred embodiments thereof, but are intended to be illustrative
rather than definitive thereof. The invention is defined in the
claims.
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