An Improved Method of Producing a Hermetical Seal for the Connecting Wires of the Filaments of Incandescent Lamps.
Year: 1891

page_text: Date of Application, 25th Apr., 1891-Accepted, 1st Aug., 1891
COMPLETE SPECIFICATION.
An Improved Method of Producing a Hermetical Seal for the
Connecting Wires of the Filaments of Incandescent Lamps.
I FRANZ WALTER, Professor in the Royal Technical Military Academy of
Vienna in the Empire of Austria Captain of Artillery 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 an improved method of producing an air-tight or
hermetical seal for the connecting wires of the filaments of incandescent lamps
without the employment of platinum.
Up to the present time platinum wire has usually been used for connecting the
service wires to the carbon filaments for the reason that no other metal in wire,
strip or other form could when molten with the glass of the globe be made to
remain perfectly airtight. Now by employing the present invention I am able to
avoid the use of the very expensive platinum and to use wires made of iron, steel,
copper, nickel, German silver or other metallic alloy and will proceed to describe
the method of carrying my invention into effect.
In order to receive the wires connected to the carbon filament and for producing
the airtight seal the globe is provided advantageously with two hollow projections
which either alone or in combination with metallic shells or capsules are charged
with a molten alloy.
When metallic shells or capsules are used the same are charged with fluid metal
alloy the coefficient of expansion of which corresponds with that of the glass
or the same are filled with an appropriate cement so that a comparatively
large sealing surface is produced which will effectually resist the influences of
temperatures.
Fig. 1 is an elevation of the glass globe with two projections.
Fig. 2 is a vertical section of the complete incandescent lamp.
Fig. 3 is a section of the improved scaling method in detail and on an enlarged
scale.
Figure 4 represents a shell which is placed over one of the projections of the
lamp to which the wire g for connection with the service wire is soldered or
otherwise attached.
The carbon filament is inserted through the wide opening a¹ of the glass globe
(Figure 1) after the same has been attached to the wires d d of iron copper or
other metal or alloy said wires being held in position by the glass or other
appropriate distance piece c.
The ends of the wires d d' enter into the hollow projections e e¹ of the globe. An
air tight seal is thereby attained inasmuch as these projections e e¹ are filled with a
metallic alloy (such as I am now making application for Patent No. 7159 of 1891)
which advantageously has the same coefficient of expansion as the glass of the
globe.
If as represented in the accompanying drawing special shells or capsules ƒƒ¹
closed at one end and composed of copper brass or other suitable metal or alloy
are used for receiving the metallic alloy an air tight seal is not only obtained
between the glass projecting parts ee of the globe and the shells or capsules f/1
but the ends of the wires d' (which are advantageously coated with the alloy
before being inserted in the shells partly filled with alloy) are entirely and airtight
enclosed.
The service connecting wires g g' are in this case as represented by Figure 4
soldered or otherwise attached to the shells or capsules ff'.
The above described process for producing a durable airtight connection of the

page_text: filament wires to the glass globe or the fittings to the same is much simpler than
the processes hitherto in use and can be carried out so readily and safely that
comparatively little waste occurs.
When the vacuum has been obtained the upper end a¹ is closed as usual and
melted tight.
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. In electric incandescent lamps the production of a durable connection between
the wires d d of iron copper or other metal or alloy carrying the carbon filament
without employing platinum in such manner that the wires d d are inserted in
hollow projections eel of the glass globe said hollow projections being filled with
a metallic alloy which can be contained in suitable shells or capsules f¹ substan-
tially as described.
2. My improved construction of incandescent lamp for avoiding the use
of platinum substantially as and for the purposes set forth in the foregoing
Specification.
Dated this 25th day of April 1801
TONGUE & BIRKBECK,
34, Southampton Buildings, Chancery Lane, London, W.C.,
Agents for the Patentee.