US 1022553 A
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J. W. HOWELL. METHOD OF FUSING LAMP FILAMENTS TO LEADING-IN WIRES. APPLICATION rlLzp'un. 16, 1907.
1,022,553, I Patented Apr. 9, 1912.
UNITED STATES T OFFICE.
JOHN W; HOWELL. 0F NEWARK, NEW JERSEY. ASSIGNOR TO GENERAL ELECTRIC COMPANY. A CORPORATION OF NEW YORK.
METHOD OF FUSING LAMP-FILAMENTS TO LEADING-IN WIRES.
To all whom it may concern:
Be it known that I, Jonx llownnn. a citizen of the United States, residing at Newark, county of Essex. State of New Jen sey, have invented certain new and useful Improvements in Methods of Fusing Lamp- Fila-ments toLeading-ln ires, of which the following is a Specification.
Incandescent lamp filaments consisting of a refractory metal, such as tungsten. molybdenum, boron, titanium. etc., may he advantageously supplied with current through a leading-1n conductor fused or welded to thc filament. Such a joint affords a rigid connectionof good conductivityand free from any carbonaceous or other vaporizablc material which might. contaminate the filament. Such awelded connection can be made to a platinum leading-in w'iro by means of an electric arc in a non-oxidizing atmosphere. The platinum leading-in wire fuses into a globule and appears to alloy or otherwise combine with the tungsten of the filament.
. According to my present invention the filament is connected by a welding or fusing operation with a leading-in conductor or wire consisting of a metal or material which does not readily alloy or combine with the material of the filament. When the two materials are of this nature, there is no danger that the fused globule will soak into the filament and possibly change its refractory qualities in immediate proximity to the Welded joint. According to the process hereinafter described, a large proportion of perfect joints are obtainable and the welding or fusing operation is performed in such a manner that the filaments are protected from the deteriorating action of the welding arc.
According to my invention, the leading-in conductor or supporting wire to which the filament is to be connected is provided with a thin tubular portion bent downward 'to form a socket for the reception of the end of the filament. The fusing arc is drawn from the lower end of the tubular socket and therefore at some distance from the filament. or more strictly speaking. atsome distance from the portion of the filament operating at incandescence when the lamp is m use.
The details of my invention will be better Specification of Letters Patent.
Application filed March 16. 1907.
Serial No. 362,610.
understood by reference to the accompanying drawing. in which- Figure l is a sectional elevation of an apparatus suitable for carrying out the welding operation: Fig. 2 is an enlarged view of the joint before the arc is formed; and Fig. 3 is an enlarged view of the finished connection.
The welding operation may be carried out in a glass envelop 1 provided at the top with-an inlet 3 through which hydrogen or other non-oxidizing gas may he continuously supplied. The envelop may be open at the bottom for the convenient introduction of a lamp stem 3 carrying a about which the several metal filaments 5 are grouped. These filaments may consist of pure tungsten or of other refractory metals and materials. Leading-in conductors or support wires 6 of copper or other suitable metal. may be arranged axially about the pedestal 4. as shown in the drawing- Before assembling the lamp, each leading-in wire is flattened at the end and then drawn through a die to shape the fiattened port-ion into a tube 7, as illustrated in Fig. 2. This tube is bent downward at a substantially right angle to the leading-in conductor and thus scrves'as a convenient fsockot for the end of a lamp filament 5.
The order of procedure is as follows: The leading-in conductor is placed in the notched end of a rod 8 which projects through an opening in the wall of the glass envelop 1. and is connected to a source of energy 9. This rod serves to conduct the arc-producing current. An electrode 10 of carbon. metal. or other suitable material is connected with the other terminal ofthe source and is movable through an opening 'll in the wall of the envelop. To produce the weld. the carbon electrode is brought in contact with the lower end of the tubular socket T and is then quick]; withdrawn to produce a heating arc. The lower end of the tube quickly fuses up and gathers in a ,g'lo-bule about the metal filament and then solidifies. The upper end of the tube is preferably left unfused, for it then acts as an anchor for the filament during the welding operation. and so keeps the filament een-.
trallv located in the fused part. Unless the filament. is thus anchored. it may more entirely out of theglobule. Owing to the Patented Apr. 9, 1912.
distance between the carbon electrode and the filament, the latter is not subjected to the deteriorating action of the arc.
It is of great importance to select for the leading-in wire, a material which does not alloy or combine with the material of the filament,as for instance, copper wire for tungsten filaments. No flux is used and the fused portion of the copper conductor remains unalloyed.
\Vhat I claim as new, and desire to secure I by Letters Patent of the United States, is,
1. The process which consists in rigidly securing a tungsten lamp filament to a copper support and then fusing a portion of said support to form a connection of good conductivity, leaving unfused a portion of said support to which said filament is secured, said unfused portion of said support being adjacent the operative part of said filament.
2. In an incandescent lamp, the combination of a tungsten filament, and a copper leading-in wire having a portion fused about said filament and an unfused portion supporting the filament.
3. The method which consists in fusing a port-ion of a metallic member about a refractory filament of material which does not readily combine with that of said memher, to form a conductive joint while the filament is maintained by another portion v of said member in a position where it will be inclosed in the fused metal.
4. The method which consists infusing the end of a copper member about a tungsten filament to form a conductive joint while the filament is maintained in proper relation to the fused end of the member by another portion thereof.
5. The combination with a refractory filament of a current conductor of material inert with respect to that of the filament loosely embracing one portion thereof and fused about a portion of the filament farther from the principal luminous portion than the portion thus embraced.
' 6. In an incandescent lamp the combination of a tungsten filament and a support wire therefor having a bent portion surrounding a part of the filament next to the operating portion thereof and fused about the filament at a point away from the operating portion of the filament.
In witness whereof, I have hereunto set my hand this 8th day of March, 1907.
JOHN \V. I-IOVELL. W'itnesses:
J. HARRY Euuxs, S. N. \VHITEHEAD.