A Method of Renewing and a Preparation for Fixing Filaments in Incandescent Lamps.
Year: 1890

page_text: Date of Application, 18th Oct., 1890
Complete Specification Left, 5th Aug., 1891-Accepted, 12th Sept., 1891
PROVISIONAL SPECIFICATION.
A Method of Renewing and a Preparation for Fixing Filaments
in Incandescent Lamps.
I, JOSEPH MÖHRLE, of Munich, in the Empire of Germany, Electrical
Engineer, do hereby declare the nature of my invention to be as follows:-
This invention consists in a method, by which incandescent lamps, in which the
carbon or other filament is burnt out or broken, may be made fit for use again by
the insertion of a new filament.
In the first instance a small slit is made in the centre of the lower or widened
part of the glass bulb. Then with the assistance of a blow flame the edges of this
slot which widens slightly in the centre, are bent open so that the small opening is
widened, the edges standing outwards.
Then the broken filament is removed and the two platina electrodes are cleaned,
the new carbon thread, of optional shape or system, is then introduced through the
longitudinally shaped opening. The connecting of the ends of the new carbon-
thread is now done immediately on the platina-electrodes by means of a new
substance composed of heated silver-graphite, of pulverized carbon (heated piasaba)
and of a solution of copper. After the new carbon filament has been fastened in
place the slot is blown by the flame, and is bent together again and the exhaust
pipe is applied, the exhausting and closing up are then done in the known
manner.
Dated this 18th day of October 1890
HERBERT & Co.,
Agents to Applicant,
A Method of Renewing and a Preparation for Fixing Filaments"
in Incandescent Lamps.
I, JOSEPH MÖHRLE, of Munich, in the Empire of Germany, 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:
The object of this invention is to provide incandescent lamps in which the
filament has been broken or burnt out, with new filaments so that they may be
used again, and the invention consists in a method of removing the broken filament
and replacing it by a new one and in a preparation by means of which the ends of
the filament may be fastened to the platinum or equivalent connecting wires within
the glass globe of the incandescent lamp.
The method consists broadly in making an opening in the lamp. removing the
broken filament and inserting the new filament by means of suitable tools and
connecting the ends to the connecting wires in the lamp, and exhausting the air
and closing the glass bulb in the usual manner.
This method may be carried out in the following manner, reference being made
to the annexed drawing. For lamps of special construction the bulb may be
divided into two halves along the line B B Fig. 5 the old filament removed and the
new one inserted and fixed, the two parts being then again connected together and
D
071

page_text: closed airtight after exhaustion. Usually however it will suffice to make a slit in
the bulb in the following manner. for introduction of the new filament. The point
of the bulb is first cut off or pierced so as to produce a very small opening, this
opening is then enlarged by use of a blow pipe flame into the form of a narrow
slit slightly widened in the middle and having outwardly turned edges, as shown
in Figs. 1 to 3. The old filament is drawn out through this slit and the platinum
wires cleaned. The new filament 6 of the shape desired is then passed through the
slit and fastened to the platinum wires.
This fastening of the filament is done by connecting the ends of the filament to
the wires by means of a plastic material which is composed of pure carbon or hard
clean vegetable charcoal (Piasaba) made into a paste with a solution of a salt of a
difficulty fusible metal, a saturated acid solution of platinum or copper being very
suitable. The pure carbon required may be produced in the known manner by
passing an electric current through benzole or other liquid hydro carbon so that
pure carbon is deposited on one of the electrodes; this need however only be done
if pure vegetable charcoal suitable for the purpose cannot be procured.
The plastic mass above described is spread upon the slightly bent wires and the
ends of the new filament pressed lightly thereon after the mass has hardened a
little and the wire has been bent to give the filament its correct position the mass
is spread over the wire so that the joint is well covered and no part of the wire
shows. The lamp is then set aside for drying. After this operation the mass must
be rendered conductive so that it offers no impediment to the passage of the current.
This may be done by the instrument shown in Fig. 4; a conductor m for instance
a copper wire carries at its end a block of carbon and is insulated throughout its
length so that the new filament may not be damaged by current from the wire m
which is connected to the current lead n, the other pole of the current is connected
to the respective wire or y. By touching the mass covering the joint of the
filament with the respective wire, a current is passed through the mass with the
result of modifying its composition so as to render it conductive as may be shown
by an incandescent lamp inserted in the circuit. After the one joint is rendered
conductive the connection is transferred to the other wire and the second joint
similarly treated. The tool is then withdrawn and the slit f is drawn together
under the blow pipe flame, the vacuum drawing tube fastened on and the bulb
exhausted and sealed in the usual manner.
Fig. 3 shows the finished lamp which cannot be distinguished from a new
lamp.
In lamps intended to be renewed from time to time by this method, the ends of
the filament may be fastened to the wires by making the latter with cylindrical
ends or spirally curved ends of any suitable shape of cross section to receive the
ends of the filaments which may be fastened by suitable cement.
The above method if carefully performed allows the filaments to be renewed
upwards of thirty times, the cost of renewal being considerably less than the cost of
manufacture of new lamps.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
1) A method of renewing incandescent electric lamps consisting in making an
opening in the glass bulb thereof removing the old filament and inserting and fixing
a new filament by suitable tools, and closing, exhausting and sealing the bulb.
2.) In the method of renewing incandescent electric lamps by production of an
opening in the glass bulb for renewal of the filament, the production in the centre
or thereabouts of a widened slit f with outwardly projecting edges substantially as
set forth.
3. The method of attaching a filament to a platinum or equivalent electrode
* consisting in fastening the same thereto by means of a paste consisting of pure

page_text: carbon or pure vegetable charcoal mixed with a solution of a metallic salt, and
subsequently converting the said paste into a conductive material by means of an
electric current passed through the joint in the manner described.
Dated this 5th day of August 1891.
HERBERT & Co.,
18, Buckingham Street, Strand, London, W.C., Agents to Applicant.