Improvements in Incandescent Electric Lamps.
Year: 1899

page_text: Date of Application, 17th May, 1899
Complete Specification Left, 8th Jan., 1900-Accepted, 10th Feb., 1900
PROVISIONAL SPECIFICATION.
Improvements in Incandescent Electric Lamps.
I, Dr. WILLIAM MENGARINI, of 109, Piazza San Bernardo, Rome, Italy, Pro-
fessor, do hereby declare the nature of this invention to be as follows:-
This invention relates to incandescent electric lamps of the kind which have
their conductors usually in the form of filaments presenting great resistance when
they are cold, but much less resistance when they are heated, and my invention
has for its object means of automatically heating the filament to the temperature
necessary to render it sufficiently conductive.
For this purpose, in connection with the circuit of the lamp I arrange a second-
ary circuit with suitable resistances; one or more of these are so situated that,
when electrically heated they heat the filament to such a temperature as to render
it sufficiently conductive for passage of the current through it.
There may be several lamps arranged in connection with the secondary circuit
and resistances, or with several such circuits, and the resistances may be of any
known kind, and these and the lamps may be combined with transformers to
increase or diminish the tension as may be required. To prevent action of the air
on the apparatus it may be wholly or partially enclosed in a casing exhausted or
charged with neutral gas.
The operation of the apparatus is such that when the current is first turned on,
the lamps give no light, but the heating resistance becomes heated and heats the
filaments, and thereupon they become luminious being traversed by the current
and meantime no current passes through the heating resistance, as the apparatus
is so arranged that if the current passes in one side of the circuit it cannot pass
in the other sides.
ABEL & IMRAY,
. Agents for the Applicant.
Improvements in Incandescent Electric Lamps.
1, Dr. WILLIAM MENGARINI, of 109, Piazza San Bernardo, Rome, Italy, Pro-
fessor, 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 incandescent electric lamps of the kind which have
their conductors usually in the form of filaments, presenting great resistance
when they are cold, but much less resistance when they are heated, and my inven-

page_text: tion has for its object means of automatically heating the filament to the tempera-
ture necessary to render it sufficiently conductive.
For this purpose, I compose a circuit with three resistances and one lamp,
as shown in Fig. 1, in which and in the other figures RRR³ denote the resist-
ances, the leads, L the lamp, and W the heating body.
One of the leads is attached to the point of connection of resistance R' with
the lamp; the other lead is attached to the point of connection of resistance R³
with R
The heating body W is inserted between the point of connection of resist-
ance with resistance R², and of resistance R³ with the lamp.
When a suitable difference of potential is applied to the leads C no current will
flow through the lamp, as it has a great resistance when cold but a current will
pass through resistance R' the heating body W and resistance R³.
So the heating body may acquire a high temperature and the lamp may be
heated. As soon as the lamp has attained the temperature necessary to make it
sufficiently conductive, a current will flow through the lamp increasing the tem-
perature of the filament, till it acquires the heat and conductivity suited to the
normal working of the lamp.
In this case if the resistances R¹R³ R³ are suitably selected no current will
any longer pass through the heating body W.
If for any reason, the temperature of the lamp becomes reduced, a current will
flow again through the heating body W raising again the temperature of the lamp.
Thus the lamp is heated in a really automatical way, depending on the well-
known principle of current distribution in a circuit composed of three constant
and one variable resistance.
It will be observed that the lamp, when in normal working condition remains
in series with one resistance. In the case represented in Fig. 1, it remains in
series with resistance R³. This is no disadvantage, as lamps of this type must
always be worked in series with a resistance, to insure safe working.
In the case of lamps fed by alternating currents it is convenient to employ
inductive resistances which can be so adjusted as to consume a minimum of energy.
There may be two lamps combined with only two resistances as shown in
Fig. 2 where one heating body W can heat in the same time two filaments.
There may be two lamps combined with five resistances, as shown in Fig. 3;
or several lamps combined with several resistances. The resistance may be made
for low potential and the lamps for a high potential, or conversely, and in this
case for lamps worked with alternating currents two branches of the circuit are
formed with insulated wire coiled on an iron core and the lamps are in connection
with a secondary circuit coiled on the same iron cores, as shown in Fig. 4.
When alternating currents are employed, the four branches of the circuit, eir:,
two resistances and two lamps may be so arranged that the two resistances are
formed by insulated wire coiled on an iron core and the lamps connected with
insulated wires coiled on the same iron core, as shown in Fig. 5.
The number of turns of wire on the iron cores, and the dimensions of the cores
depend on the difference of potential of the leads and on the difference of poten-
tial required by the lamps.
The resistances and the heating body may be of any known kind and if it is
desirable to prevent the action of the air on the apparatus, it may be wholly, or
partially enclosed in a casing exhausted, or filled with neutral gas.
Figs. 6, 7, 8 shew how some of these arrangements can be practically carried
out in constructing incandescent electric lamps. Thus Fig. 6 represents a lamp
arranged as shewn diagrammatically in Fig. 1, the heating body being repre-
sented as a helix surrounding the incandescent body. Fig. shews a lamp
arranged according to diagram Fig. 2, the heating body being a flat metal helix
on a plate of refractory material, between two incandescent bodies.
Fig. 8 shews a lamp arranged as diagrammatically shewn in Fig. 5, with the
iron core and windings of insulated wire, accommodated within the lamp holder,

page_text: while two incandescent bodies are placed in the bulb along with the heating
body which is represented as a basket of metallic wire.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I declare that what I claim is :-
In an incandescent electric lamp, the combination of an incandescence body
of such kind that after previous heating it allows sufficient current to pass to
render it incandescent, or several such bodies, with resistances of such value and
so arranged as to form a circuit between two points of which there is a difference
of potential when the incandescence bodies are under the normal working tem-
perature; and no difference of potential when they are at the normal working
temperature, so that a heating body inserted between these two points is traversed
by the maximum current, when the incandescence bodies are cold, raising their
temperature; and is traversed by a current diminishing as the incandescent bodies
approach their normal working temperature until when this is attained, no cur-
rent passes through the heating body.
Dated this 8th day of Tanname 1000
ABEL & IMRAY,
Agents for the Applicant.