Improvements in Arc Lamps.
Year: 1891

page_text: Date of Application, 26th Nov., 1891
Complete Specification Left, 26th Aug., 1892-Accepted, 1st Oct.. 1892
Improvements in Arc Lamps.
1, FREDERICK RICHARD BOARDMAN, of 3 Wesley Road, Southend, in the
County of Essex, Electrical Engineer, do hereby declare the nature of this invention
to be as follows :-
My invention relates to arc lamps, and it has for its object the making of a
simple, compact, and efficient lamp. The parts being few, and simple in character,
it enables me to make an efficient lamp at a moderate cost.
The invention is
applicable to lamps using either a continuous or an alternating current of electricity,
and the point of the arc may be kept approximately at one point (called a focussing
lamp), or otherwise as desired.
The two carbons are preferably arranged in a vertical manner, the lower one
being secured to a holder attached to a moveable framework for a focussing lamp,
or to a fixed framework for a non-focussing lamp. The upper carbon is held by an
insulated holder which is secured to a brass tube or rod placed vertically above it.
The current connections are made to the two carbons in any usual or convenient
manner. The vertical brass tube, which carries the upper carbon holder, is adapted
to move freely within an iron tube that forms a moveable core within two bobbins;
the upper one having a series conducting coil wound thereon, the other, or lower
one, being shunt wound. These coils are in line with each other, and they have a
brass tube in the centre, common to both, in which the iron core is also adapted to
move freely. To the bottom of the iron core is secured two lengthening bars, and
at the lower end of each of these a short connecting rod is pivoted.
Each
The outer end of each connecting rod is connected to two pivoted arms, oppo-
sitely placed, each arm carrying a small brass pulley grooved to fit against the
carbon or against the vertical brass tube which serves as the carbon holder.
pivoted arm is extensible-as regards its length-and by means of a spring, pressure
is exerted through each grooved pulley upon the carbon or its holder. The
fulcrum of each pivoted arm is fixed in some cases, but it may be made moveable
against spring pressure or a weight, and if so the pivoted arm need not be made
extensible. A fixed or adjustable stop may be used to limit the outward range of
the pivoted arms.
When the current is off, the iron core with its connected pivotal arms drop as
far as the stop will allow, and the two grooved pulleys opening outward on circular
arcs release the upper carbon or its holder, allowing the same to fall until the
upper carbon is in contact with the lower one. As soon as the current passes
through the lamp and the coils are excited, the iron core is drawn upward and the
arc is struck between the carbons, in the usual manner. Any increase in the
resistance, such as that due to the burning away of the carbons, causes the main
current to fall off, and this, weakening the magnetic effect due to the series coil
results in lowering the core and upper carbon until an equilibrium is established.
It will thus be seen that the differential effect of the series and shunt wound coils,
acting upon an iron core common to both coils, and directly regulating the distance
between the carbons, produces a simple and compact lamp with few parts, and not
liable to get out of order.
The same method of regulating the relative position of the upper carbon is also
employed in simultaneously lifting the lower carbon, in a well known manner, for a
focussing lamp. To the upper carbon holder two cords are attached, each passing
over a separate pulley to which the outer end is attached. These pulleys are

page_text: oppositely placed, and each carries a smaller pulley on the same axle. Similar
cords pass over the small pulleys, the inner ends being secured thereto, while the
outer ends are secured to the moveable frame-work first mentioned as carrying the
lower carbon. The circumferences of the large and small pulleys are so propor-
tioned to each other as to compensate for the greater consumption of the positive
carbon when using continuous currents, but when alternating currents are to be
used, the two pulleys of each pair are made of the same diameter. It is desirable
to counterweight the parts so that the carbons are brought into contact with each
other when the current is not passing. A suitable globe may be suspended from
any convenient part of the frame.
Dated this 25th day of November 1891.
FAIRFAX & WETTER,
433, Strand, London, Agents for the Applicant.
Improvements in Arc Lamps.
I, FREDERICK RICHARD BOARDMAN, of 3 Wesley Road, Southend, in the
County of Essex, Electrical Engineer, 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 arc lamps, and it has for its object the making of a
simple, compact and efficient lamp. As the parts are few, and simple in character,
the lamp can be made at a moderate cost. The invention is applicable to lamps
using either a continuous or an alternating current of electricity, and the centre of
the arc may be kept approximately at one point (in a lamp called a focussing lamp)
or otherwise, as desired.
In the further description of the invention reference is made to the accompanying
drawings, in which
Fig. 1 is an elevation of a focussing lamp, with the coils in section to show the
core.
Fig. 2 is an elevation of a clutch gear acting upon the carbon holder to raise the
upper carbon.
Fig. 3 is an elevation of another gear for the same purpose but slightly differing
from Fig. 2.
Fig. 4 is an elevation of the arrangement of pulleys for the simultaneous move-
ment of the carbons, differing somewhat from the arrangement shown in Fig. 1.
In the drawings, the upper carbon a is arranged in a vertical manner above the
lower carbon b, the latter being secured to a holder forming a part of a moveable
framework C, if for a focussing lamp as shown in Fig. 1, but if the lamp is not
required to focus then the framework may be fixed. The upper carbon a is held
by an insulated holder secured to or forming part of a brass tube or rod e placed
vertically above it. The current connections to the carbons are made in any con-
venient manner.
The brass tube e (with its holder d) is adapted to move freely within an iron tube/
that forms a moveable core within bobbins or coils of insulated conductor. The
upper coil is wound with thick wire to form the series coil, and the lower coil h
is wound with fine wire to form the shunt coil; and the coils are suitably wound
and proportioned to act as hereinafter stated. The coils and are in line with
cach other, with a central brass tube common to both in which the iron core fis
adapted to move freely. To the bottom of the core f two lengthening bars (or
their equivalent a collar) are secured, and at the lower end of each of these a short
connecting rod is pivoted.
The outer end of each connecting rod jis pivotally connected to one of two

page_text: pivoted arms or levers which are oppositely placed, each arm & carrying upon its
pivotal connection with a small friction pulley of brass grooved to fit against the
upper carbon or its holder e, to act as a clutch. Each pivoted arm k is extensible
-as regards its length-and by means of a spring m pressure is exerted through
each grooved pulley upon the carbon or its holder e. The fulcrum of each arm k
'is fixed in some cases, but it may be made moveable, or the arm itself slide in a
slot when acted upon by spring pressure or a weight, and if so the pivoted arm
need not be extensible. The arrangement preferred, however, is shown in Fig. 1.
A fixed or adjustable stop n may be used to limit the outward range of the
pivoted arms.
When the current is off, the iron core f with its connected arms &, drop as far as
the stop n will allow, and the two grooved pulleys -opening outward on circular
arcs release the upper carbon holder e, allowing the same to fall until the upper
carbon a is in contact with the lower carbon b. As soon as the current passes
through the coils, the series coil being strongest, the iron core is drawn upward
and by means of the clutch or friction pulleys acting upon the holder tube e the
upper carbon is lifted and the arc is struck between the carbons. Any increase in
the resistance, such as that due to the burning away of the carbons, causes the
main current in the series coil to fall off, thus reducing its magnetic effect upon the
iron core to keep it up. At the same time, as the shunt coil is usually and con-
veniently connected across the main terminals of the lamp, o and p, the magnetic
effect due to the shunt coil is increased, which results in lowering the core and
upper carbon until an equilibrium is established. It follows, therefore, that the
differential effect of the series and shunt wound coils-acting upon an iron core
common to both coils and directly regulating the distance between the carbons
through the intervention of the clutch gear as above described, produces a simple
and compact lamp, with few parts, and not liable to get out of order.
The same method of regulating the position of the upper carbon a is also
employed in the relative lifting or lowering of the lower carbon at the same
time in a well known manner, for a focussing lamp. To the upper carbon
holder d, two cords are attached, each passing over a separate pulley r, to a part
of which the outer end of its cord is attached. These pulleys rare oppositely
mounted on any convenient part of the lamp, and each one carries a smaller pulley
(fast with it) on the same axle, both pulleys turning together. Similar but
separate cords pass over the small pulleys, but in the opposite direction, the inner
ends of the cords being secured to the said small pulleys, and the outer ends to
the moveable framework which carries the lower carbon b, as shown in Fig. 4.
The circumferences of the large and small pulleys are so proportioned to cach
other as to compensate for the greater comsumption of the positive carbon-when
using continuous currents-but when alternating currents are to be used-or as a
modification-the two pulleys of each pair may be made of the same diameter; or
a single groove pulley on each side may be used as shown in Fig. 1. A regulating
out s or an equivalent screw stop may be put on the holder tube e, or at the top of
the lamp to regulate the full extent of the arc.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
:―
1. In an arc lamp, the combination of a series coil g and a shunt coil , with an
iron core common to both coils placed vertically above the carbons a and b, and clutch
gear acted upon by the said core, substantially as and for the purpose herein shown
and described.
2. In an arc lamp, the combination of a series coil g, a shunt coil in line
with each other, a tubular iron core common to both coils, a rod or tube e
with carbon holder d, grooved clutch pulleys 1, pivoted arms k, springs m, con-
nections and between the said core and arms k, and current connections

page_text: between the terminals o and p and the coils and h whereby the coils act in a
differential manner upon their core, substantially as and for the purpose herein
shown and described.
Dated this 25th day of August 1892.
FAIRFAX & WETTER,
433, Strand, London, Agents for the Applicant.