Improvements in Incandescent Electric Lamps.
Year: 1890

page_text: Date of Application, 9th Sept., 1890
Complete Specification Left, 9th July, 1891-Accepted, 9th Sept., 1891
PROVISIONAL SPECIFICATION.
[Communicated from abroad by JOHN BLEECKER TIBBITS, of Hoosack, in the
State of New York, United States of America, Clergyman.]
Improvements in Incandescent Electric Lamps.
1, WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake and Co. Patent
Agents, 45 Southampton Buildings, in the County of Middlesex, do hereby
declare the nature of this invention to be as follows:-
This invention relates to an improved method of constructing incandescent lamps
for use in series circuits.
The main object of the said invention is to provide simple and effectual means
for preventing the interruption of "series" incandescent lamp circuits, (should the
filament of one of the lamps be broken) at a minimum of expense and without the
employment of cumbersome or complicated devices.
Lamps of this class when connected in series, must be provided with some means
for keeping the circuit closed in case the filament of one of the lamps should become
ruptured or burned out," because in such a case the circuit is opened or interrupted,
and the remainder of the lamps located in the circuit are thus extinguished.
To overcome this defect series lamps are usually each provided externally with a
magnetic cut-out consisting of a high resistance shunt connected to the terminals
of the lamp, so that upon the breaking or rupture of the lamp filament, the whole
current would pass through the shunt wires and energise the magnet, the armature
of which in operating is adapted to cut out the shunt and form a closed circuit
around the broken lamp. Obviously a cut-out of this description adds greatly to the
cost of the lamp as well as complicating to the system.
Now an important feature of the said invention consists in supporting a straight
filament in metallic carrying arms and sealing the same within a glass globe, the
said arms being separated at their upper ends by a block of non-conducting material,
and the whole being so arranged that if the filament breaks, the said arms
automatically engage or come in contact with each other, thereby forming a closed
circuit and thus effectually "cutting out" the filament from the circuit.
In carrying my invention into practice I form the filament of a straight. carbon,
the ends of which are mounted in two spring arms, which in case the latter becomes
ruptured, operate in such a manner that the current is transferred from the
filament to suitable contact portions provided on the two metallic spring arms,
thereby maintaining a continuous circuit.
The upper portion of the glass globe of the lamp is reduced in diameter and
slightly elongated, forming a neck which is capped over and has the metallic con-
ducting wires passing through the same and hermetically sealed therein. The lower
ends of the said conducting metallic wires are electrically connected to depending
spring arms which serve as the carbon carrying arms; the same being made of
suitable spring metal adapted to withstand heat and yet retain its spring and be a
good conductor of electricity. The arms are separated at the upper ends by an
interposed insulating block of mica or other suitable material. Each arm is drilled
to receive two raised hubs formed on opposite faces of the separating block and
enlarged washers of vulcanite, and suitable metallic rivets passing through said
arms, washers and block are used for the purpose of firmly securing all the parts
together. The said arms extend downwardly and are bent inwardly that is to say
toward each other and the inner adjacent faces thereof are provided each with a
small metallic button made preferably of platinum, which buttons are about th inch
apart when the arms are in their normal position. The lower extremity of each

page_text: arm is adapted to receive and retain an end of a filament, the extremities being
preferably split and forming a spring clamp for this purpose.
The arms are so mounted and secured that a slight "set" is produced, which
servos to automatically spring the lower ends together whenever the opposing force
set up by the filament is removed by the breakage thereof.
In the event of a rupture of the filament and the consequent decrease in length
of the same due to the action of the are formed, the arms owing to the removal of
the lateral pressure from them, spring toward each other until the metallic buttons
thereon come into contact, thus causing the current to be uniformly maintained,
without affecting the other lamps on the same circuit and preventing the formation
of dangerous ares such as other cut-outs sometimes allow.
1 am aware that lamps have heretofore been provided with means adapted to
short circuit the electric current from the filament when it became broken or
ruptured, which consisted of two current carrying spring arms adapted to come into
contact with each other, but the action generally ecurred prematurely or long
before a rupture occurred, from the fact that a bow shaped filament was used so
that the filament when heated to incandescence became soft to a certain degree,
and the tension of the spring overcame that of the bow-shaped filament before the
latter was ruptured.
I overcome this defect by using a straight filament wherein no tension of the
filament is required to oppose that of the springs that is to say, which will offer
greater resistance to the action of the springs than a bow-shaped filament.
Dated this 9th day of September 1890.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.
COMPLETE SPECIFICATION
Improvements in Incandescent Electric Lamps.
1, WILLIAM ROBERT LAKE of the firm of Haseltine Lake & Co., Patent Agents,
45 Southampton Buildings in the County 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:-
My invention relates to incandescent electric lamps for use in series circuits.
The main object of my said invention is to provide for preventing the interruption
of "series incandescent lamp circuits Ly the breakage or burning out of the
filament of one or other of the lamps in such circuit, and to accomplish this result
in a more simple and inexpensive manner than heretofore and without the
employment of cumbersome or complicated devices..
Lamps of this kind or class, when connected in series are usually provided with
means whereby, in case the filament of one or other of the lamps should become
ruptured or burned out, the current will be short-circuited therefrom and the circuit
thus kept closed thereby preventing extinction of the remainder of the lamps
connected in the said circuit.
For this purpose external magnetic cut-outs have been hitherto employed,
consisting of a magnet included in a high resistance shunt connected to the terminals
of the lamp, so that, upon the breakage or rupture of the lamp-filament, the whole
current will pass through the shunt and energise the magnet, the armatura of which
operates to cut out or short-circuit the said shunt and form a closed circuit around
the broken filament. Devices of this description, however, are expensive and
complicated.
Electric incandescent lamps, moreover, have been provided, for this purpose, with
current-carrying spring arms arranged to hold a bow-shaped or hent filament, and
adapted to come into contact with each other upon the rupture of the filament, but,
in a lamp so constructed, this action generally takes place prematurely, or before a

page_text: rupture of the said filament occurs, or before the filament is burned out, by reason
of the latter becoming, when heated to incandescence, to a certain degree soft or
pliable and thereby, owing to its shape, permitting the tension of the said spring
arms to overcome the resistance of the filament to bending or snapping.
An important feature of my said invention consists in the use of a straight
filament supported in conducting carrying-arms sealed within a glass bulb or globe,
and separated at their upper ends by a block of non-conducting material, and so
arranged that, if the filament breaks, the said arms automatically engage or come
in contact with each other, thereby forming a closed circuit and thus effectually
"cutting out" the said filament from the circuit. By using a straight filament, I
provide for opposing the tension of the spring conducting arms by the resistance to
compression of the said filament; therefore greater resistance is offered to the
action of the said arms, and the said filament is effectually prevented from yielding
or giving way under the action thereof when heated to incandescence.
My said invention comprises, morcover, other improvements hereinafter set forth.
In the accompanying drawing, I have shown how my said invention may be
conveniently and advantageously carried into practice.
Figure is a side elevation, partly in vertical section, showing an electric
incandescent lamp constructed according to my said invention.
Figure 2 is a vertical section, drawn to an enlarged scale, showing details of
construction.
Figure 3 is a similar view to Figure 1, showing a modification hereinafter
described.
Figure 4 is a view illustrating a method of connecting or arranging my improved
lamps.
Like letters indicate corresponding parts throughout the drawing.
A. is the globe or bulb of the lamp. B, B are the wires or conductors. C is the
filament.
The upper portion of the globe or bulb A is reduced in diameter and slightly
elongated, forming a neck which is capped over and has the metallic wires or
conductors B passing through the same and hermetically sealed therein in the usual
manner. D. D are arms formed of suitable spring metal which is adapted to
withstand heat and yet retain its clasticity and be a good conductor of electricity.
The arms D. D* are separated at their upper ends by an interposed insulating
block E of mica or other suitable material, and each of the said arms is drilled to
receive two raised hubs or extensions E (Figure 2) formed on opposite faces of
the said insulating block. F, F are washers of vulcanite or other suitable non-
conducting material, and F, F are metallic rivets passing through the said arms,
washers and insulating block E, for the purpose of securing all the parts firmly
together. The arms D, D* extend downwardly and are first bent inwardly, that
is to say, towards each other, and the inner adjacent faces thereof are preferably
provided each with a small platiuum or other metallic button or extension D'. The
lower extremities of the arms D are bent outwardly and are provided with suitable
sockets D adapted to receive and retain the filament C. The said sockets D' are
preferably split so as to form spring clamps, adapted to grip the filament and retain
it firmly in position.
The arms D, D* are mounted and secured so as to have a slight set inwards or
towards each other, which, serves in the event of a rupture of the filament, and the
consequent decrease in length of the same due to the action of the arc formed, to
cause the said arms, owing to the removal of the lateral pressure from them, to
spring towards each other and bring the metallic buttons or extensions D' into
electrical contact, thus again completing the circuit and causing the current to be
uniformly maintained without affecting the other lamps in the same circuit, and,
moreover, preventing the formation of dangerous arcs such as other cut-outs
sometimes allow.
In Figure 3, I have shown a modification which I prefer to employ in cases
where it is desirable or necessary to use, in conjunction with a lamp, one or more

page_text: auxiliary lamps which will be consecutively and automatically lighted by the com-
pletion of the electric circuit thereto, should the carbon or other filament in the
first or preceding lamp break as herainbefore mentioned. This arrangement is
very advantageous where a single lamp is sufficient for the illumination of a room
or other space, the auxiliary lamp being included in the circuit should the filament
of the other lamp break.
n
Gis a central arm, wire or conductor arranged between the arms D. D", and
provided with a button or extension (i' adapted to engage with and form electrical
contact with the button or extension D' on the arin D when the filament C is
ruptured. His a small spiral or other spring, which nets to draw the contact
points and D' together, but which must be insulated from one or the other of
the conductors D, G; the filament C', in its normal state, is of sufficient strength
to resist the force exerted by the said spring 11. The central conductor ( is
secured in its central position by the insulating material E, which may be formed
in two parts or pieces, and the spring II is, as above stated, properly insulated
from electrical contact at its poin's of fastening, so as not to interfere with tho
normal action of the lamp. 1 is a metallic link covered with enamel or other non-
conducting material and secured to the arm D and to the central conductor G, and
intended to prevent any giving or yielding of the latter under the action of the
spring 11.
In Figure 4, I have shown a method of connecting the lamps when a single
auxiliary lamp is employed in combination with a lamp such as that shown in
Figure 3. The said second or auxiliary lamp is, in this case, preferably of similar
construction to that described with reference to Figure 1. A is the first lamp,
A is the second or auxiliary lamp, A is the main wire or conductor. The terminals
or leading-in wires B of the first lamp A are connected to the main wire A³, and
one of the terminals or leading-in wires B of the second or auxiliary lamp A'
is connected by means of a wire A to the central conductor G of the lamp A,
the other terminal or wire B of the lamp A' being connected to the main wire
or conductor A³.
If the filament in the lamp A becomes ruptured, the arm D° will be moved
under the action of the spring II, and the contact points G' and D' will be drawn
together (as shown in Figure 4) thus completing or closing the electric circuit to
the lamp A through the said arm D, the central conductor G, and wire A³.
If the filament in the lamp A' becomes ruptured, the arins D, D will spring or
move together as hereinbefore mentioned and form a path for the electric current.
I am thus enabled at all times to maintain a closed electric circuit, so that other
lamps in the circuit will not be affected in any manner by failure of the filament in
any individual lamp.
It is obvious that any convenient number of lamps such as those described
with reference to Figure 3 may be connected together in this manner, but I
prefer to employ a single auxiliary lamp coupled or connected as shown in
Figure 4.
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 :-
First. An incandescent electric lamp, comprising a straight filament and two
spring conducting arms which support and are held apart by the said filament, and
which are adapted to move into contact with each other should the said filament be
broken or burned out, for the purpose above specified.
Second. The combination of suitable wires or conductors, two spring conducting
arms electrically connected therewith, an insulating body interposed between and
secured to the upper portion of the said arms, metallic buttons, projections or
extensions secured to, or formed on adjacent sides of the said arms at or near the
free ends thereof, an Í a straight filament mounted in the free ends of the said arms
at right angles or approximately at right angles thereto, substantially as, and for
the purposes, set forth.

page_text: Third. The modification of my improved lamp wherein one of the conducting
arms which support the straight filament is arranged in combination with a central
conductor and is held out of contact therewith by the said filament, but, when the
latter is broken or burned out, will make contact with the said central conductor,
for the purpose above specified.
Fourth. The combination of two conducting arms, a straight filament mounted
thereon at right angles or approximately at right angles thereto and at or near the
free ends thereof, and a central conductor or conducting wire suitably insulated
and connected to one of the said arms by an insulated spring (with or without a
link of enamel coated metal, or other non-conducting material, between the central
conductor and one of the said arms), substantially as described.
Fifth. The combination of an incandescent electric lamp having two conducting
arms, a straight filament mounted thereon at right angles or approximately at right
angles thereto and at or near the free ends thereof, and a central conductor connected
to one of the said arms by an insulated spring, and another lamp having two spring
conducting arms, and a straight filament mounted thereon at right angles or
approximately at right angles thereto, and at or near the free ends thereof, the
said lamps being suitably connected, substantially as, and for the purposes, above
specified.
Daten Cais foth any of JJANG 1991.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.