An Improved Method and Apparatus for Connecting Carbon Filaments to Metallic Conductors and for similar Purposes.
Year: 1889

page_text: COMPLETE SPECIFICATION.
[Communicated from abroad by HERMANN LEMP, of 19, Allen Avenue, Lynn,
Massachusetts, United States of America, Electrical Engineer.]
An Improved Method and Apparatus for Connecting Carbon
Filaments to Metallic Conductors and for similar Purposes.
I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake, and Co., Patent Agents,
Southampton Buildings, in the ("ounty of Middlesex, do hereby declare the nature
of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :—
This invention relates to a method of and apparatus for making an electrical and
mechanical connection between carbon, or material having similar properties and
another body, and is useful especially for connecting the filament of an incandescent
electric lamp to the metallic conductors passing from the interior of the bulb of the
lamp to the exterior thereof for connection with the electric circuit.
It has heretofore been proposed to connect the filament and the leading in wire by
immersing them in a liquid or gas which deposits carbon under the action of heat
and then passing a heating electric current through the metallic wire and the filament
and from one to the other, at the point where they are to he joined. In other words
the heating current passes through both the conductor and the filament through the
point of contact between them the two parts to be united being in an electric circuit
in series with one another and a carbon deposit upon both conductors being depended
upon to make the joint. Owing to the difference in the conductivity of the carbon
and the body to which it is to be connected, the deposit of carbon takes place mainly
on the carbon filament and to a less extent upon the conductor, while besides it but
slightly passes the division line between them. It thus happens that the joint is often
weak, mechanically and of poor conductivity.
By this process the carbon can only be united with a conducting material and in
the case of metals which fuse at a lower temperature there is danger of fusing them in
the operation. The process is therefore adapted only to the union of carbon with
refractory metals such as platinum.
These objections are overcome by this invention which consists mainly in forming
the joint by means of the deposit of carbon made to take place only on the carbon
filament, such carbon alone forming the path for the current while the body to which
it is to be connected is simply retained in proximity to the filament so that the
deposit on the filament will lap over and engage the adjacent body thus connecting
the two.
By the present method the carbon may be connected to a non-conducting material
if the latter be adapted to withstand the heat accompanying the operation.
In practising this invention it may in some cases be necessary or desirable to
convey the current to the portion of the carbon upon which the deposit is being made
by a portion of the material to which the carbon is to be connected and in this case a
part of the deposit may be upon both bodies and tend to join them in the method
heretofore practised; but such joint made by the old method is not the one depended
upon to mechanically unite and electrically connect the two bodies, which will be
further united by a deposit formed wholly upon the carbon and extending therefrom,
so as to engage and preferably embrace a portion of the other body that is not in
circuit while said deposit is being made.
This invention consists further in a special apparatus whereby a joint may be
formed in accordance with the improved process.
In the accompanying drawings,
Figures 1 and 2 are a sectional view and side elevation, respectively of a joint
made by the method forming the subject of this invention.

page_text: Figures 3 and 4 represent a side elevation and plan view respectively of the body
connected with the carbon to make the joint represented in figures 1 and 2.
Figure 5 represents a diagram illustrating the method of making the joint shown in
figures 1 and 2 in which the current is introduced to the carbon wholly independently
of the body with which the carbon is to be connected, which body need not
necessarily be of conductive material.
Figures 6, 7 and 8 represent another form of body to be connected with the
carbon.
Figures 9 to 12 inclusive, represent the formation of the joint with such body, a
portion of which is depended upon to convey the current to the carbon.
Figure 13 illustrates another modification of the joint made by the method forming
the subject of this invention.
Figure 14 illustrates a joint made by the method commonly employed prior to
this invention.
Figure 15 is a plan view of an apparatus embodying this invention for forming
the joints between the ends of a carbon filament and metallic conductors.
Figure 16 is a side elevation thereof.
Figure 17 a detail showing the support for the metallic conductors in side elevation..
Figures 18 and 19 show sectional details on lines x and y of figure 15 showing the
supports and circuit connecting devices for the carbon filament.
Figure 20 is a side elevation with part in longitudinal section; representing a
modification used for carbons and metallic conductors of different shape from those
used with the apparatus represented in figures 15 to 19.
Figure 21 is a plan view of the instrument represented in figure 19, and
Figures 22, 23 and 24 show details representing the several supports or clamps in
elevation.
The most effective manner of forming the joint is to place the carbon in juxta-
position to the body to which it is to be united in such a way that there shall be
parts of such body at opposite sides of the carbon or wholly surrounding the same
so that the deposit in building up upon the carbon will enter or wedge in as it
were between the same and the outside body.
A very strong and effective joint may be formed by passing the ends of the carbon
filament for an electric lamp through a metallic conductor a as indicated in figures 1
and 2, which is formed into a loop or eye a¹, through which the carbon b, passes as
indicated in figure 5.
As it is not essential in practising this method that the metallic conductor should
be extremely refractory copper may be used, and has several advantages as a
conductor for an incandescent electric lamp, which will be hereinafter mentioned.
When the metallic conductor is made of copper wire it may be prepared for
uniting with the carbon, as shown in figures 3 and 4 by flattening a portion of the
end of the wire and then piercing the said flattened portion to make the opening a¹,
through which the carbon is passed. After the carbon b has been placed in proximity
to the conductor a as shown in figure 5, the parts are placed in a fluid that will
deposit carbon in the well known manner, and a current passed through the portion of
the carbon adjacent to the conductor a. The current is passed through the carbon b
by means of conductors applied thereto in any suitable manner, as indicated at
points e, f by means of apparatus to be presently described, or in any other suitable
way. As will be observed the path of the current is through the carbon and does not
have to pass through the material of a.
Owing to the refractory nature of the carbon, a very large current can be passed
through it, causing a rapid deposit of carbon upon it, which builds out from the
carbon until finally it engages the body a as indicated in figure 5, and owing to
the fact that the body a, has portions at opposite sides of the carbon, or, in fact,
wholly surrounding it, the deposit wedges between the said portions, and if continued
will build out upon the body a, embedding it in the deposit to a greater or less extent
as indicated in figures 1 and 2 thus forming a joint of great strength mechanically and
affording a very close electrical connection. In the construction illustrated in figures 1

page_text: and 2, the deposit builds up at both sides of the connecting body, forming a mechanical
connection similar to that of a rivet, which does not depend upon the adhesion between
the two bodies united, but upon the actual strength of the two bodies, which cannot
be separated without rupture of one or the other of them. It is also apparent that, as
the current does not pass through the body a in forming the joint, the joint does not
depend at all upon the conductivity of the part a, and the carbon might be connected
with a non-conducting material by. this method when desired. It is not, however,
essential that the body a, to be connected with the carbon should be wholly out of
circuit as a portion of said body may be depended upon to convey the current to the
carbon, the deposit upon which will then engage another portion of said body to form
the joint or a part of the joint.
As shown in figures 6, 7 and 8 the body a, to be connected with the carbon is a flat
strip of conducting material provided with an opening a0, of larger diameter than the
carbon, the said strip being then bent, as shown in figure 8 to form a pair of
jaws a², a³, between which the end of the carbon b is held, as shown in figure 9, with
the carbon passing through the opening a without touching the conductor a around
such opening. The conductor e is then placed in contact with the carbon beyond the
opening a, and the current passed from the conductor a, to the conductor e, through
the portion of the carbon b, that extends from the jaws a a³, to the conductor e. This
will cause a deposit to be formed upon the conductor b, which will finally fill the
opening a, as shown at b', figures 10 and 11, and thus fasten the carbon to the
conductor a, as before described. If the current is continued after the opening a¹,
has been thus filled, there will be a secondary action, as the current will pass through
the metal to the point a¹0, and the deposit will subsequently be formed mainly on the
portion of the carbon between the opening a10, and the conductors e, as shown at 62,
figures 10, 11 and 12, and by the combined effect of the two deposits 61, 62, a very
strong joint can be made.
The operation of making the joint shown in figure 13, is substantially the same as
that last described; but in this construction the body a, has arms a*, a³ at opposite
sides of the carbon, which rest in contact with the body a, at the base of the
arms a, a. The current is passed from a, through the carbon b to the conductor d,
beyond the prongs a20, making a deposit on the said carbon, which finally engages the
said prongs a20, after which a secondary deposit is formed between the said prongs
and the conductor e.
In the method of joining carbons with conductors heretofore commonly practised,
and illustrated in figure 14, the current is passed from the metallic conductor a,
through the carbon b, to the conductor e; but the portion 63, of the deposit formed on
the carbon itself does not contribute at all to the strength of the joint, which depends
wholly upon the continuation 6, of said deposit below the dotted line x, which
deposit, surrounds the extremity of the conductor a. A joint made by this method
depends wholly upon the adhesion of the conductor a, and portion 6, of the deposit or
upon the strength of the said small portion 64, of the deposit, and is not only weak
mechanically, but is of poorer conductivity than the joint formed by the herein
described method.
An important advantage in the use of copper as a connector for a conductor to be
connected with a carbon filament arises from the greater expansibility of the copper
when heated, from which it results that if the carbon has partially broken away from
the metal, making a joint of poor conductivity, the rise in temperature due to the
increased resistance will expand the copper and press it into close contact with the
carbon, thus diminishing the resistance.
In order to properly hold the filament and conductor to which it is to be united
and pass
the current through the filament or other carbon, I employ an apparatu s such as
indicated in figure 15, and the following figures. In this apparatus the metallic
conductors of an electric lamp to which the filament b, is to be united according to the
present invention, I sustain by a stand or support d. The parts of the instrument are
supported on the base A of insulating material, and the support d¹, is of insulating

page_text: material supported on the end of an arm d², pivoted at d³, on a stand or upright d*,
and acted upon by a spring d³, that presses the block d', down upon the metal
conductors resting on the stand d. The clamping device may be readily lifted against
the stress of the spring d³, to release the metallic conductors and permit the insertion
of others. The base A, is also provided with two supports e, e¹, which should be made
of copper or other conductive material, and are provided with shoulders at their upper
ends, upon which the extremities of the filament rest, as shown after passing through
the openings in the ends of the metallic conductors a. The ends of the filament are
held upon these supports by clamping jaws e, e³, pivoted upon uprights e*, e³, and
acted upon by springs es, e', that tend to press the ends of the jaws e³, against the
sides of the flat filament, so as to hold the same firmly, as shown in figure 18.
One entire support and co-operating clamp is insulated from the other, each
being connected with a conductive stripes, e, supported on the base A, and constituting
the conductors by which the current is carried to and from the filament.
The body of the filament & may be further supported, if required, upon a platform B
which is shown as provided with an adjustable gage B', that may be used to set the
filaments in proper position to give uniformity in length of a number of filaments
successively treated in the machine.
In order that the current may pass through only a small portion of the filament
at each side of the ends of the connecting wires d, circuit connecting devices are
provided consisting of uprights f, f¹ of conductive material electrically connected
together by a conducting base f said uprights touching the branches of the
filaments at a short distance from the ends of the metallic conductors a and in
order to make a good electrical contact the branches of the filament are pressed
against the uprights f,f, by clamping devices 3, 4, which may consist of blocks
of copper supported on springs f³, f³, themselves supported on uprights f", f³, on
the base A.
In the construction shown in figures 15 and 16 the springs f³, fo, extend by the
ends of the clamping jaws e³, e³, so that the one operation of pressing together the
handle ends of said clamping jaws, as shown in dotted lines, figure 15, will wholly
release the filament, and by then raising the clamp for the metallic conductors the
joined carbon and filament may be removed from the machine and new ones
inserted.
In order to make the joint after the filament and conductors have been supported
and clamped in proper position with relation to one another, as shown in figure 15,
the terminals of the current supplying circuit are connected with the strips es, e⁹,
the current passing from one of said strips, as es, to the clamp e³, and one end of the
filament thence along the said filament to the circuit connector f; ƒ³, thence across
by the connection f³, to the connector f¹, f, thence along the filament to the
other clamp el, e³, and out by the strip e. The current is applied in this manner
while the instrument is immersed in a fluid bath that deposits carbon under the action
of heat, and as all the conductors that are in circuit, with the exception of the
short portions of the filament, are of low resistance, a very large current may be
employed causing a very rapid deposit on the short portions of the filament
between the clamps that engage it which deposit, when it builds out, engages
and surrounds the ends of the metallic conductors through which the filament is
passed.
The shape of the supports and holders, obviously may be modified in order to
co-operate with conductors or filaments of various forms.
In the construction illustrated in figures 20 to 24, inclusive, the metallic
conductors a, a¹ are sealed into a tubular neck c, of glass, and the support d for
the main conductors is of proper shape to receive such neck, which is held securely
thereon by a clamp do, shown as consisting of a spring strip supported on uprights do,
provided with projections at their upper ends, which may be screw heads, as shown
having a smaller neck between said projections and the upright. The spring do,
has a slot of a width equal to the diameter of the neck, and at one end an

page_text: opening communicating with said slot large enough to permit the passage of the
head through it, as clearly shown in figure 21. By slipping the spring along in
the direction of the arrow, figure 21, until the opening comes in line with the
head the spring will be released and may be turned aside to permit the removal of the
lamp necks E, and a reverse movement will fasten the clamps after another lamp-neck
has been placed in position.
The devices that support and clamp the end of the filament b, may be constructed as
best shown in figure 24, each of said devices consisting of an upright e20, provided
with a stationary arm e¹¹, that rests beneath the filament b. The arm e22, is slotted, as
shown, at e, where it engages its pivot, so that it can be slipped laterally off from the
filament b, when the latter is to be released, a handle e2, facilitating the manipulation
of the clamp arm e²².
The circuit connecting device by which the main portion of the filament is short
circuited and the current carried across from one to the other of the two short
portions on which the deposit is to be formed, consists of a supporting lever f10,
(best shown in figure 23,) pivotally supported on an upright f", and a firm contact
between said support and filament is effected by a clamping lever f¹³, pivoted
upon an upright f14, and adapted to be acted upon at its other end by a spring
holder, which presses it against the filament.. The pivoting of the lever f10,
causes the pressure on the two sides of the filament to be equal. After the deposit
has been made in substantially the same way as before described the lamp neck C,
and connected filament may be removed by first turning aside the spring f16, and
lifting up the clamp f¹³, then slipping back the two clamping arms e20, and then
turning aside the clamp 610, after which a new lamp-neck and filament may be placed
in proper position with relation to one another, being supported and held in such
position while a joint is being made.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed as communicated to me
by my foreign correspondent, I declare that what I claim is :—
1. The herein described method of connecting a filament of other carbon
conductor with another body consisting in forming a deposit of carbon on such
filament by passing an electric current through it until the mass of deposited carbon
engages the adjacent body or parts thereof contiguous to such carbon.
2. The herein described method of connecting a carbon filament or conductor to
another body consisting in forming a carbon deposit upon the filament by passing an
electric current through a portion of such filament passing between parts of the body
to which it is to be connected.
3. The herein described apparatus for fastening carbon filaments to a conductor
consisting of a pair of insulating supports for the two branches of the filament,
and pivoted clamping jaws co-operating therewith, a pair of connected conductors
engaging the branches of the filament, and spring clamps co-operating therewith and
extended to be engaged and operated by the pivoted clamping jaws, substantially as
and for the purpose described.
4. In a machine for mounting filaments, a pair of insulated supports for the two
branches of the filament and pivoted clamping jaws co-operating therewith, and
a pair of connected conductors engaging the branches of the filaments and spring
clamps co-operating therewith and extended to be engaged and operated by the pivoted
clamping jaws, substantially as and for the purpose described.
5. In a machine for mounting filaments, the combination, with the support that
holds the metallic conductors, of clamps that engage the filament near the ends thereof
and other clamps that engage the legs of the filament at a short distance from the
first mentioned clamps, whereby the short sections of each leg of the filament between
the two clamps that engage each leg may be brought into proximity but out of electrical
contact with adjacent parts of said conductors.
6. In a machine for mounting filaments, the combination with a bar extending across

page_text: from one to the other leg of the filament and pivoted between them, of a bar also
extending across from one to the other leg of the filament and constituting, with the
pivoted bar, a clamp for the filament, and a short circuit connection between the two
legs of the filament as and for the purpose described.
Dated this 9th day of July 1889.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.