US3189778A

US3189778A - Lamp filament connection

Info

Publication number: US3189778A
Application number: US169323A
Authority: US
Inventors: William L Brundige
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1962-01-29
Filing date: 1962-01-29
Publication date: 1965-06-15
Anticipated expiration: 1982-06-15

Description

June 15, 1965 w. L.. Bai-@memes LAMP FILAMEFQT CONNECTION F1165, mh 9,9; 3.962

A Wim FIG. 2.

INVENTOR. W/ l /HM @RUND/6E.

United States Patent O gna This invention relates to electrical devices and, more particularly, to an improved mechanical and electrical connection between the filament and lead-in conductor or supporting member of an incandescent electric lamp.

ln the manufacture of certain types of electric lamps, such as high-Wattage tubular heat lamps having coiled laments of relatively heavy wire for example, 'the size and rigidity of the lead-in conductor makes it dicult to connect it to the filament. Que frequently used method ot joining these members together is to enlarge the end of the conductor and force it into the coil until it becomes caught behind the end turns of the lament. A juncture of this type wherein the end of the conductor is flattened to provide a spade-like tip that efiects a force-ht with the ilament coil is disclosed in US. Patent No. 2,830,217, issued April 8, 1958.

Another and older method of etiecting such junctures is to form threads on the end of the conductor either by a cutting operation or by winding a wire tightly around the conductor at the proper pitch. The threaded end of the conductor is then screwed into the end of the coiled lilament thus threadably coupling the members together. Threaded conductors and connections or" this character are illustrated and described in US. Patent llo. 2,449,679, issued September 2l, 1948.

The lead-tolament connection has also been etlected in some cases by Welding the members together.

lt is accordingly the general object of this invention to provide an improved iilarnent connection that does not require a critical dimensional t of the members and thus eliminates this problem and overcomes other disadvan tages of the prior art structures.

A more specitic object is the provision of a ilament juncture that is simple, inexpensive, and reliably locks the members in opposite electrical engagement without any additional parts or critical interiitting of the members.

The foregoing objects, and others which will become obvious as the description proceeds, are achieved in accordance with this invention by providing a recess and a pair of abrupt transverselyextending shoulders at a preselected point along the conductor, inserting this recessed portion into the coiled lilament, and then permanently deforrning and collapsing intermediate portion of the lilament into the recess. rlhe partly flattened lilament portion is retained Within the recess by the shoulders thereby securely locking the members together in electrical engagement and preventing the filament from slipping along the conductor in either direction.

The recess and retaining shoulders can be formed at the same time that the lilarnent turns are collapsed by simultaneously applying sutlicient heat and pressure to the filament turns and the underlying portion of the inserted conductor, preferably in the presence of an inert atmosphere.

A better understanding of the invention will be obtained by referring to the accompanying drawing where 1n:

EEG. l is an elevational view of one form ol' electric lamp embodying my invention, a central portion ot the lamp being omitted for convenience of illustration;

FIG. 2 is an enlarged perspective View of the connecting end ci a lead-in conductor in accordance with one embodiment ot the invention;

3 is a cross-sectional view of the conductor taken alo.-g the line lll-lll of FIG. 2, in the direction of tn arrows;

EG. 4 is a plan View of the conductor shown in FIGS. 2 and 3 connected with one end of the coiled filament in accordance with this invention;

FiG. 5 is a view corresponding to that shown in FIG. 4 but with a portion of the filament omitted for illustrative purposes;

FIG. 6 is a cross-sectional view of the connection along the line fl-Vl of FlG. 4;

FlG. 7 is an elevational view ot another type of juncture according to the invention; and

FiG. S is an enlarged cross-sectional view along the line Vill-Vlll of FIG. 7, in the direction of the arrows.

While the improved lament connection of this invention can be employed in various types ot lamps and electrical devices, it is especially suited for use in conjunction with high-vvattage tubular infrared-generating lamps and has accordingly been so illustrated and will be so described.

With specific reference to the drawing, in FlG. l there is illustrated a tubular heat lamp 1@ comprising a quartz e '-felope l1. of relatively small diameter that is closed at each end by a press seal i4. Sealed Within the envelope is a coiled filament 13 of helical configuration Wound from a suitable refractory metal wire, such as tungsten for example. The filament extends longitudinally of the envelope and is centrally mounted therein by means or" lead-in conductors 16 of molybdenum or the lilre embedded in each of the press seals and by a plurality of spaced supporting discs 2li ot tantalum, or other suitable refractory material, that are inserted between adjacent turns of and are anchored to the lilament at preselected points along its length. The lead-in conductors 16 are fastened to the usual ribbon-and-terminal assemblies embedded in each of the press seals to facilitate connecting the lamp to a voltage source. In order to prevent the ilament 15 from sagging during use, the lead-in conductors lo are so spaced during the sealing-in operation that the lament is tensioned slightly and kept taut. The envelope contains the usual filling of a suitable inert gas such as argon or the like.

A detailed description of a lamp of the foregoing type is given in US. Patent No. 2,864,025 dated December 9, S.

ln accordance with one form of the present invention a preselected portion of each of the lead-in conductors il@ 1s deformed to provide a llat 22 proximate to, but spaced mwa' ly from one end of the conductor, as shown in 3. The reduction in cross-section of this that in the case ot a conductor wire i6 or the lille having a substantially uniform diameter d1, a fiat opredetermined length L, width W, and thickness t is provided, as is illustrated. Preferably, the reduction in cross section of the wire is such that the thickness t of the iiat 22 is no greater than about Vs of the wire diameter d1 so as to form pronounced recesses 23 (see llG. 3) on opposite sides of the conductor, which recesses are terminated at each end by transversely c2 extending shoulder that are Well delinea rise abruptly from the ilat The rounded coiour of the conductor is, accordingly, abroA tly altere.. by the s" .t

whereas the extreme end portion 2d of the conductor slightly smaller than the inner diameter 2 of coiled ilament lo so that the llattened portion of the conductor le can very readily be inserted into th end section of li that it extends for a plurality of turns of the fil such as three turns thereof as in the case illu FGS. 4 to 6.

To er'iect the juncture according to the embodiment shown in FiGS. 4 to d, the ilattened portion of the conductor is iirst inserted into the coiled filament and positioned so that the flat Z2. is located beyond the end turns and within an intermediate portion 28 of the filament. The lament turns comprising the overlying intermediate portion are then permanently deformed and partly collapsed by simultaneously heating this portion of the filament and compressing it in a direction substantially normal to the surface of the iat. ln order to avoid deleteriously oxidizing the filament or conductor, heating and bending of the filament turns is preferably performed in an inert atmosphere such as nitrogen.

The aforesaid heating and compressing operation partly collapses the intermediate portion 2S of the filament it@ into :the recesses 23 and forces the bent turns into intimate engagement with the dat Z2, as illustrated in FGS. 4 to 6. Moreoven'as shown most particularly in FlG. 6, the outermost turns of the collapsed intermediate portion 28 of the tilament are caught and seated behind the transversely extending shoulders 26 located at each end of the flat thus securely locking the collapsed turns within the recesses and coupling the filament and conductor wire in positive electrical and mechanical engagement.

Heating and bending of the filament turns that com-y prise the intermediate portion 2d can be conveniently accomplished by means of la pair of `suitably shaped jaws (not shown) having electrically heated work faces.

As a `specific example of the actua-l dimensions involved, in the case of a 5 G0 watt infrared heat lamp having a lead-in Wire 0.025 in diameter a coil with an inside diameter of about 0.040 Wound from tungsten Wire .0098 in diameter, satisfactory connections have heen obtained by employing a dat approximately 1/16 long, 0.035" Wide and about 0.015 thick.

ht should be noted that the intermediate portion of the filament to be collapsed need only be heated sufficiently to render it easily deformable. rihus, temperatures in the order of approximately 200 C. in the case of a tungsten filament Will sufllce.

As shown in the alternative embodiment illustrated in FIGS. 7 and 8, the desired mechanical and electrical juncture can also be achieved in accordance with this invention by utilizing a straight or unmodied piece of conductor wire 16a, that is, one which is not provided with a ilat or deformed portion near one end. The conductor wire in this case is fabricated from a relatively soit metal such as annealed nickel, copper or the like and has a diameter d3 that is slightly less than the inside diameter d2 of the iilament ld, as indicated in E2G. 7.

After the end of the conductor lo has been inserted into the proper position within an intermediate portion 23a of the filament this portion and the underlying segment of the conductor are simultaneously heated and coinpressed along a line normal to the wire axis until the partly collapsed lameut turns are at least partly embedded in the conductor at a plurality of points 3l) located on opposite sides of the conductor and inward from its proximate end7 as shown in FIG. 7. The applied heat and pressure are such that the distance :c between in the same direction as th considerably less cl3 of 'the Wire, as indicated in Flo `ity of transverse grooves are ii conductor by the col- A ent tu Thus, in this embodiment the deformation of the conductor and partial collapse of the overlying intermediate portion of the filament are both accomplished by means of a sirele operation. will be obvious from FlG. 7 that i, heat and pressure are applied lto form the same combination of pronounced recesses and abrupt retaining shoulders las in the case of the first embodi ient shown in fFlG-S. l to 6.

` nient Att* i g-oaci. and resul-tnt during the cooling-down it will oe obvious, of course, that the aforementioned ed in the surface of the conductor,

by stamping, to provide a preformed conductor as in `ofthe b ment shown in FEES, Z to 6.

om the foregoing that vthe objects of toe inven have been achieved by providing an improved electrical and mechanical junction between a ment and lead-in conductor or support which conand inexper 7e to fabricate.

embodiments of the improved conbeen described in detail, these are given have nection merely by Way of example and various structural and procedural modifications can accordingly be made without departing trom the spirit and scope of this invention. For example, Ithe iilarnent does not have to be coiled throughout its length but may be provided with coiled end sections that `are interlocked with the lead-in member in the manner described.

l claim as my invention: Y

Il. In an electric incandescent lamp, the combination of a refractory wire filament having a coiled end section, and a lead-in conductor that is smaller in diameter than the inside diameter of said coiled end section and has a flat that is located proximate but inv/ard from one end of said conductor aud lits freely within said coiled end section, the rounded contour of said lead-in conductor being abruptly altered by said tlat thereby .providing an elongated recess that is terminated at each end by transversely-extending sharply-defined shoulder, said being located within an intermediate portion of said coiled end section and of suflicient length to accommodate more than one turn of said coiled end section, the turns of said coiled end secon overlying said fiat being collapsed into recess seated between said shoulders thereby loclcinfr `said conductor in mechanical and positive electrical engagement with said iilament.

2. ln combination with a iilament of refractory metal Wire having a coiled end section comprising a plurality of spaced turns, a conductor that is freely insertable into said coil end section and has an `elongated recess Which is located proximate to but inward from one end of said conductor and is defined by a pair of abrupt transverselyextending shoulders, said conductor being inserted into said coiled end section a distance such that the recessed portion of said conductor is loc-ted Within an intermediate portion of said coiled end section and the proximate end portion of said conductor projects therebeyond toward the filament proper, a plurality of the tums comprising the overlying intermediate portion of said coiled end section being permanently deformed and collapsed into said recess and seated therein between and in interlocking relationship with said shoulders, thereby mechanical- 6 References Cited by the Examiner UNITED STATES PATENTS 1,379,036 5/21 Moorhead 313-333 X 2,667,592 1/54 Hilder 313-344 X 5 2,830,217 4/58 Hodge 313-333 X 2,864,025 12/58 Foote et al 313-274 DAVID I. GALVIN, Primary Examiner. JOHN W. HUCKERT, ARTHUR GAUSS, Examiners.

Claims

1. IN AN ELECTRIC INCANDESCENT LAMP, THE COMBINATION OF A REFRACTORY WIRE FILAMENT HAVING A COILED END SECTION, AND A LEAD-IN CONDUCTOR THAT IS SMALLER IN DIAMETER THAN THE INSIDE DIAMETER OF SAID COILED END SECTION AND HAS OF FLAT THAT IS LOCATED PROXIMATE BUT INWARD FROM ONE OF SAID CONDUCTOR AND FITS FREELY WITHIN SAID COILED END SECTION, THE ROUNDED CONTOUR OF SAID LEAD-IN CONDUCTOR BEING ABRUPTLY ALTERED BY SAID FLAT THEREBY PROVIDING AN ELONGATED RECESS THAT IS TERMINATED AT EACH END BY A TRANSVERSELY-EXTENDING SHARPLY-DEFINED SHOULDER, SAID FLAT BEING LOCATED WITHIN AN INTERMEDIATE PORTION OF SAID COILED END SECTION AND OF SUFFICIENT LENGTH TO ACCOMMODATE MORE THAN ONE TURN OF SAID COILED END SECTION, THE TURNS OF SAID COILED END SECTION OVERLYING SAID FLAT BEING COLLAPSED INTO RECESS AND SEATED BETWEEN SAID SHOULDERS THEREBY LOCKING SAID CONDUCTOR IN MECHANICAL AND POSITIVE ELECTRICAL ENGAGEMENT WITH SAID FILAMENT.