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Publication numberUS3295016 A
Publication typeGrant
Publication dateDec 27, 1966
Filing dateJan 2, 1964
Priority dateJan 2, 1964
Publication numberUS 3295016 A, US 3295016A, US-A-3295016, US3295016 A, US3295016A
InventorsAyres Reginald J, Paul Vargo, Russell Arthur P
Original AssigneeGen Electric
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Manufacture of electric incandescent lamps
US 3295016 A
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Description  (OCR text may contain errors)

Dec. 27, 1966 R. J. AYRES ET AL 3,295,016

MANUFACTURE OF ELECTRIC INCANDESCENT LAMPS 2 Sheets-Sheet 1 Filed Jan. 2, 1964 14 m3 F1 .3. $353M 5 2 lnven tovs. Regnabd d. Agves Paul, Vavggo Dec. 27, 1966 R. J. AYRES ET AL 3,295,016

MANUFACTURE OF ELECTRIC INCANDESCENT LAMPS 2 Sheets-$heet 2 Filed Jan. 2, 1964 1TWVTT CTS1 Reg lfiatd J. Agfes PauL Verge Avflthuv P. Russett United States Patent M 3,295,016 MANUFACTURE OF ELECTRIC INCANDESCENT LAMPS Reginald J. Ayres, Cleveland, Paul Vargo, Lyndhurst, and Arthur P. Russell, South Euclid, Ohio, assignors to General Electric Company, a corporation of New York Filed Jan. 2, 1964, Ser. No. 335,018

Claims. (Cl. 31617) This invention relates to a method of making an electric incandescent lamp and a mount therefor.

One type of incandescent lamp in common use at present for certain lighting applications such as, for example, instrument panel and vehicular interior or dome lighting, is in the form of a miniature double-ended tubular or so-called festoon lamp comprised of a tubular glass envelope or bulb in which is sealed a lamp mount consisting of a filament connected across a pair of lead-in conductors or wires which are respectively sealed through the opposite ends of the envelope. The envelope is customarily provided with an inert gas filling and with end terminals or contacts generally in the form of metal end caps or bases cemented or otherwise fastened to the opposite ends of the envelope.

The methods heretofore employed to fabricate such miniature type double-ended incandescent lamps ordinarily have been quite complicated and expensive. In addition to requiring a considerable amount of hand labor, such prior lamp making methods have involved the use of a number of different types of complicated and expensive lamp making machines such as, for example, a mount machine for fabricating the lamp mount, a tubulating and sealing machine for attaching an exhaust tubulation to one end of the envelope and sealing the lamp mount into the opposite ends of the envelope, an exhaust machine for evacuating the envelope and then filling it with an inert gas and tipping off the exhaust tubulation, and a basing machine for attaching the metal end caps or bases to the opposite ends of the envelope. Because of these considerations, the domestic manufacture of such miniature type double-ended incandescent lamps by the previously known methods would be too costly to be economi cally feasible.

It is an object of the invention therefore to provide a novel and inexpensive method of making double-ended type incandescent lamps which lends itself to fully automatic high speed production manufacture thereof and requires a minimum amount of lamp making equipment;

Another object of the invention is to provide a novel method of fabricating a double-ended type incandescent lamp which permits the complete fabrication of the lamp on a single lamp making machine with a minimum of manufacturing operations.

Briefly stated, in accordance with one aspect of the invention, -a lamp mount holder is inserted through a glass lamp envelope having openings in its opposite ends and a lamp mount then fabricated on the through-inserted end of the holder, after which the envelope and the mount holder with the formed mount held therein are then repositioned to locate the mount in sealing position within the envelope and the mount then sealed into the opposite ends of the envelope. The interior of the envelope may be provided with an inert gas filling which may be introduced thereinto, after the sealing of the mount into one end of the envelope, by flushing the interior of the envelope with an inert gas directed thereinto through the open other end of the envelope from a flushing nozzle inserted thereinto, and then sealing the mount into the said other end of the envelope immediately upon withdrawal of the flushing nozzle therefrom.

In accordance with another aspect of the invention, the mount is formed on the through-inserted end of the 3,295,916 Patented Dec. 27, 1966 mount holder by gripping a length of wire between the said holder and a second holder located exteriorly of the envelope, severing the wire length at a region between the said holders to form two separate lead-in wires, and then connecting a filament across the severed ends of the gripped lead-in wires.

Further objects and advantages of the invention will appear from the following detailed description of species thereof and from the accompanying drawings.

In the drawings, FIGS. 1 to 7 illustrate the successive process steps involved in the fabrication of an electric incandescent lamp in accordance with one form of the method comprising the invention;

FIG. 8 is a perspective view of the finished lamp produced by the method according to the invention, and

FIGS. 9 and 10 are views illustrating the successive initial steps involved in fabricating an electric incandescent lamp according to a modified form of the method comprising the invention.

Referring to FIGS. 1 to 7 showing the preferred lamp making method according to the invention, a doubleended glass lamp envelope or bulb 1, preferably of tubular shape as shown and provided at its opposite ends with openings 2 and 3 in reduced diameter neck end portions 4 and 5, respectively, is first placed over an upstanding lead-in wire holder or chuck 6 so as to elfect insertion of the holder completely through the envelope 1 through the openings 2, 3 in its opposite ends. In such position, the envelope 1 is disposed vertically with its opopsite end openings 2, 3 vertically aligned with one another, and it may be suitably supported in such position as by resting its lower end on an envelope support collar 7 surrounding the holder 6.

With the holder 6 thus inserted through theenvelope 1, the end of a straight length of wire 8, from which the lead-in wires 9, 10 (FIG. 2) of the lamp are formed, is then inserted in and firmly gripped by the holder 6. For such purpose, the holder 6 is provided with a vertically extending wire receiving opening or passageway 11 (FIG. 1) in its upper end within which passageway the wire 8 is received and gripped between suitable clamping jaws (not shown) located within the holder 6. The length 8 of wire is preferably fed from a continuous supply reel 12 thereof disposed directly above the upper end of the lead-in wire holder 6, and it is additionally gripped by an upper holder 13 suitably comprised of clamping jaws, such as a pair of clamping jaws 14, 15, so as to extend vertically in substantial coaxial alignment with the envelope 1 and the openings 2 and 3 thereof. While gripped in the holders 6, 13, the wire length 8 extending therebetween is severed from the remainder of the supply 12 thereof at a point above the upper holder 13, as denoted by the dash-dot line 16 in FIG. 1, 'by suitable wire cutting means (not shown).

The severed length of wire 8 gripped in the holders 6 and 13 is next cut in two at a point 'between the two holders, as denoted by the dash-dot line 17 in FIG. 1, to thereby form two separate lead-in Wires 9 and 10 (FIG. 2) of substantially equal length. The adjacent or facing severed inner end portions of the gripped lead-in wires 9 and 10 are then suitably reshaped to provide filament connection portions, as by forming the said wire ends with partial Z-bends 18 as shown in dotted lines in FIG. 1 and with filament clamping hooks 19, between which a coiled filament 20 such as a tungsten wire coil is then connected or clamped as shown in FIG. 2 to thereby complete the fabrication of a lamp mount 21 on the through-inserted lower holder 6 and upper holder 13. After formation of the filament clamping hooks 19 but before clamping of the filament coil 20 therein, the leadin wires 9, 10 may be axially repositioned relative to one another, as by movement of the lower holder 6 toward or away from the upper holder 13, in order to thereby accurately space the filament connection portions or hooks 19 of the lead-in wires the necessary predetermined distance apart to effect clamping of the desired length of the filament coil 20 therebetween.

Following the completion of the lamp mount 21, a conventional type getter material 22, such as a mixture of powdered aluminum and powdered zirconium for example, is applied onto the portions of the lead-in wires 9, immediately adjacent their hooked ends 19, such as on the angular Z-bend portions 18 thereof. The getter material 22 serves to prevent immediate blackening of the lamp envelope l'upon initial operation or light-up of the completed lamp. The getter material 22 may be applied onto the lead-in wires 9, 10 as coatings of a suspension of the aluminum and zirconium powder admixture in a suitable binder such as nitrocellulose dissolved in a suitable thinner such as amyl acetate. The binder is burned out of the getter coatings 22 by the heat attending the subsequentl sealing of the lamp mount 21 into the lamp envelope 1.

While still maintaining the supporting grip of the holders 6, 13 on the lead-in wires 9, 10 of the lamp mount 21, the glass envelope 1 and lamp mount 21 are next repositioned relative to one another, as by moving the envelope 1 upwardly around the mount 21, to thereby introduce the mount into the envelope and locate these parts in sealing position relative to one another as shown in FIG. 3, with the filament of the lamp mount more or less centered lengthwise within the envelope 1. The

upward movement of the envelope 1 to, and the supporta ing thereof in its said sealing position may be eifected by an envelope holder 23 suitably comprised of a pair of clamping jaws 24, 25 and vertically movable relative to the mount carrying holders 6, 13. With the mount 21 and envelope 1 thus held in sealing position, the upper neck end 4 of the envelope is then suitably heated, as by means of gas fires 26 directed thereagainst from burners 27, to soften the glass and fuse it around the lead-in wire 9 positioned therewithin. Simultaneously with the heating and softening of the upper neck end 4 of the glass envelope 1, the interior of the envelope is flushed with a suitable inert gas such as nitrogen which is directed upwardly through the envelope. The flushing gas may be directed into the envelope 1 by gas jets from a-flushing nozzle positioned at the lower neck end -5 of the envelope and preferably inserted a slight distance into the lower neck end opening 3 of the envelope. The flushing nozzle may conveniently be constituted by the upper end of the lead-in wire holder 6 itself which, as shown in FIG. 1, may be provided for such purpose with one or more nozzle openings 28 (two in the particular case illustrated) in its top end face for directing jets 28a of the inert gas upwardly into the envelope. The openings 28 communicate with an interior passageway 29 extending through the holder 6 and connected to a source of inert gas supply. The heating of the glass envelope by the gas fires 26 to effect the fushion of the upper end 4 of the envelope 1 also serves to burn out the organic binder in the getter coatings 22 on the lead-in wires 9, 10 of the lamp mount, the resulting volatile decomposition products thus formed being carried out of the envelope by the inert gas flowing therethrough. The removal of the binder and its decomposition products from the envelope is essential because of the detrimental effect they have on lamp operation even if small traces thereof remain in the finished lamp.

When, during the continuance of the heating and fusion of the upper neck and 4 of the envelope 1 and the simultaneous flushing of inert gas upwardl therethrough, the glass of the neck end 4 has become sufficiently softened to collapse down onto and embed the enclosed lead-in wire 9, the softened neck end 4 is then compressed firmly around the lead-in wire 9, as between a pair of opposed pressing jaws 30 as shown in FIG. 4, to thereby form a more or less flattened external stem press or seal portion 31 on the envelope within and through which the lead-in wire 9 is then hermetically sealed so as to extend endwise therefrom. As shown more particularly in FIG. 8, one or both of the flat sides of the stem press 31 are formed with a shallow V or U-shaped groove 32 extending longitudinally of the envelope more or less axially thereof, which groove or grooves are formed by a suit-ably shaped ridge or ridges in the opposed press or work faces of the pressing jaws 30.

Following the sealing of the lead-in wire 9 of the lamp mount 21 into the upper neck end 4 of the glass lamp envelope 1, the envelope is again flushed with an inert gas which may be directed upwardly into the envelope by gas jets 28b from the nozzle openings 28 in holder 6. The inert flushing gas employed at this stage of the lamp making process, however, is of the composition which is desired for the final filling gas in the finished lamp, argon being the preferred gas for such purpose. The flushing of the envelope 1 with the argon or other inert filling gas must be carried out in such a way as to insure the removal and replacement of all the gaseous atmosphere within the envelope by the argon or other inert filling gas, inasmuch as the presence in the final sealed lamp of any residual atmospheric air, or of any decomposition products of the organic binder employed for the getter coatings 22, would be highly detrimental to the operation of the completed lamp. To this end, therefore, it is essential that the flushing nozzle or holder 6, in this phase of the lamp making operation, be inserted at least part way, e.g., at least one millimeter or 8021s in the particular case illustrated, into the open lower neck end 5 of the envelope in order to thereby avoid the aspiration of atmospheric air into the envelope by the jets 28b of filling gas which are directed into the envelope from the nozzle openings 28 in the flushing nozzle 6. Simultaneously with the flushing of the envelope 1 with the final inert filling gas, the lower neck end 5 of the envelope is suitably heated, as by means of gas fires 33 directed thereagainst from burners 34, to soften the glass and fuse it around the lead-in wire 10 positioned therewithin. The heating of the lower neck end 5 of the envelope by the gas fires 33 also serves to further ensure the complete burning out of the organic binder in the getter coatings 22 on the lead-in wires 9, 10 and the removal of the volatile decomposition products thereof from the envelope by the filling gas directed into the envelope from the flushing nozzle 6.

When, during the continuance of the heating and fusion of the lower neck end 5 of the envelope 1 and the simultaneous flushing of the argon or other inert gas filling upwardly thereinto, the glass of the neck end 5 has become sufiiciently softened to be readily compressible, the inert gas flushing of the envelope is interrupted by shutting off the gas supply to the flushing nozzle 6. The combination flushing nozzle and holder 6 is then immediately moved downwardly to withdraw it from within the lower neck end 5 of the envelope and stretch out the coiled filament 20 to the desired final length, and the softened glass of the neck end 5 then immediately compressed firmly around the lead-in wire 10, between a pair of opposed pressing jaws 35, to thereby form a more or less flattened external stem press or seal portion 36 substantially identical to the upper stem press 31 and through which the lead-in wire 10 is hermetically sealed so as to extend endwise therefrom. The stem press 36 thus formed, like the other stem press 31 at the other end of the envelope, is pressed with a similar shallow V or U-shaped groove 37 in one or both of its flattened sides, which groove or grooves are formed by a suitably shaped ridge or ridges in the opposed press or work faces of the pressing jaws 35.

The formation of the lower stern press 36 completes the hermetic sealing of the lamp mount 21 into the envelope 1 so that the latter then constitutes a completely hermetically sealed enclosure containing the desired inert filling gas. All that then remains to complete the fabrication of the lamp according to the invention .is to bend the outwardly projecting portions 9', of the lead-in wires 9, 10 back around the ends and down against the flattened sides of the respective stem press seals 31, 36, in the manner shown in FIG. 7, so as to lie flat thereagainst within the grooves 32 and 37 to thereby form the contact terminals for the lamp. This wire bending operation may be performed either on the same machine employed to seal the lamp mount 21 into the envelope 1, or on a separate machine. The completed lamp 38 as thus formed (FIG. 8) is particularly suitable for use in conventional push-pull clip type lamp sockets, the flattened stem press ends 31, 36 of the lamp being adapted to be inserted or wedged between the spring clip socket contacts which are shaped to snap into the grooves 32, 37 in the stem press ends 31, 36 so as to engage and make electrical contact with the bent-over or contact terminal portions 9', 10' of the lead-in wires 9, 10 lying therewithin.

The modified lamp making process according to the invention as shown in FIGS. 9 and 10 differs from that described previously only in the manner of fabricating the lamp mount 39 on the through-inserted end of the holder 6. Thus, referring to FIG. 9, after the envelope 1 has been placed over the upstanding lead-in wire holder 6 to effect the insertion of the latter completely through the envelope 1, a pair of precut lead-in wires 9 and 10 of the proper length are positioned in spaced vertically extending side-by-side relation with each other with the wire 10 upstanding from and gripped by the combination holder and flushing nozzle 6 and the other wire 9 upstanding from and gripped by a pivoted holder 40 which is mounted for pivotal movement in a vertical plane through an arc of approximately 180, as indicated by the dash-dot line in FIG. 9. A filament is then connected across the upper ends of the lead-in wires 9, 10 to thereby complete the fabrication of the lamp mount 39. As before, the filament connection ends of the lead-in wires 9, 10 may be formed with hooks 19 for clamping the filament 20 to the lead-in wires. After application of getter coatings 22 to the lead-in wires 9, 10, the lead-in wire 9 is then swung upwardly in an are, as by pivotal movement of the holder 40, into an upside down position as shown in dash-dot lines in FIG. 9, so as to be in vertical alignment with but spaced the proper distance endwise from the other lead-in wire 10 for sealing into the upper neck end 4 of the glass lamp envelope 1. The mount 39 as thus reformed is then in readiness for the sealing thereof into the envelope 1 which, for such purpose, is raised into sealing position around the mount 39, as shown in FIG. 10. From this point on, the remainder of the lamp making process is then exactly the same as that described hereinbefore in connection with FIGS. 1 to 6.

From the above description, it will be apparent that we have provided a greatly simplified and economical method of making a double-ended incandescent lamp as compared to the methods heretofore employed for such purpose. In addition to confining the number of lampmaking operations to a minimum, the method according to the invention lends itself to fully automatic lamp manufacture on a single unitary-type lamp-making machine of simplified construction and without any wastage of the materials employed in the fabrication of the lamp, such as the glass parts therefor. Because of all the many attendant advantages, the use of the lamp-making method comprising the invention therefore renders the manufacture of double-ended incandescent lamps an economically feasible and entirely practical undertaking.

Although preferred embodiments of our invention have been disclosed, it will be understood that the invention is not to be limited to the specific process steps and procedures described but that they may be widely modified within the spirit and scope of our invention as defined by the appended claims.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. The method of making a mount structure for an electric incandescent lamp comprising the steps of feeding a length of wire from a continuous supply thereof and temporarily gripping it at spaced points therealong, severing the said length of wire from the remainder thereof and cutting it in two between the gripped regions thereof to form two separate lead-in wires, reshaping the adjacent severed ends of the gripped lead-in wires to form spaced filament connection portions, and then connecting a filament across the said filament connection portions of the gripped lead-in wires.

2. The method of making an electric incandescent lamp comprising the steps of temporarily gripping and supporting a straight length of wire at spaced points therealong, severing the said wire length between the gripped regions thereof into two separate lead-in wires and spacing their severed ends a predetermined distance apart, connecting a filament across the severed ends of the gripped lead-in wires to form a lamp mount, positioning the lamp mount in sealing relation within a glass lamp envelope while maintaining the supporting grip on each of said lead-in wires, and then sealing the lamp mount into the said envelope.

3. The method of making an electric incandescent lamp comprising the steps of temporarily gripping and supporting a straight length of wire at spaced points therealong, severing the said wire length between the gripped regions thereof into two separate lead-in wires and spacing their severed ends a predetermined distance apart, connecting a filament across the severed ends of the gripped lead-in wires to form a lamp mount, positioning the lamp mount, while maintaining the supporting grip on each of its said lead-in wires, in sealing relation within a glass lamp envelope with the lead-in wires of the mount disposed within respective openings in opposite ends of the envelope, fusing and sealing one of the open ends of said envelope around the respective mount lead-in wire positioned therewithin, flushing the interior of said envelope with a stream of inert gas directed thereinto from its other open end, and then fusing and sealing the said other end of the envelope around the respective mount lead-in wire positioned therewithin.

4. The method of making an electric incandescent lamp comprising the steps of inserting a lead-in wire holder through a glass lamp envelope through openings in opposite ends thereof, forming a lamp mount on the through-inserted end of said holder, repositioning the envelope and said holder relative to one another to locate the lamp mount in sealing position within the envelope, and then sealing the said lamp mount into the opposite ends of the envelope.

5. The method of making an electric incandescent lamp comprising the steps of inserting a lead-in vw're holder through a glass lamp envelope through openings in opposite ends thereof, forming on the through-inserted end of said holder a lamp mount comprised of a pair of lead-in wires and a filament connected therebetween, repositioning the envelope and said holder relative to one another to locate the lamp mount in sealing position within the envelope with the filament thereof disposed within the envelope and the lead-in wires located within respective open ends of the envelope, fusing and sealing one of the open ends of said envelope around the respective mount lead-in 'wire positioned therewithin, flushing the interior of said envelope with a stream of inert gas directed thereinto from its other open end, and then fusing and sealing the said other end of the envelope around the respective mount lead-in wire positioned therewithin.

6. The method of making .an electric incandescent lamp comprising the steps of inserting a lead-in wire holder through a glass lamp envelope through openings in opposite ends thereof, forming a lamp mount on the throughinserted end of said holder, applying on said lamp mount a getter material suspended in an organic binder, repositioning the envelope and said holder relative to one another to locate the lamp mount in sealing position within the envelope, heating the lamp envelope to burn out the said organic binder while simultaneously flushing the interior of said envelope with a stream of inert gas directed thereinto from one of its open ends and passing out through its other open end fusing and sealing the said other end of the envelope, again flushing the interior of i said envelope with an inert gas directed thereinto from a flushing nozzle positioned within its said one open end, and then fusing and sealing the said one end of the envelope.

7. The method of making an electric incandescent lamp comprising the steps of inserting a lead-in wire holder through a glass lamp envelope through openings in the opposite ends thereof, clamping a length of wire between the through-inserted end of said holder and a second holder located exteriorly of said envelope, severing the said length of Wire at a region between the said holders to form two separate lead-in wires held in the respective holders, reshaping the adjacent severed ends of said lead-in wires to form spaced filament connection portions, mounting a filament on the said filament connection portions of said lead-in wires to form a lamp mount, repositioning the envelope and said holders relative to one another to locate the said lamp mount in sealing position within the envelope, and then sealing the said lamp mount into the opposite ends of the envelope.

8. The method of making an electric incandescent lamp comprising the steps of inserting a lead-in wire holder through a glass lamp envelope through openings in the opposite ends thereof, clamping a length of wire between the through-inserted end of said holder and a second holder located exteriorly of said envelope, severing the said length of wire at a region between the said holders to form two separate lead-in Wires held in the respective holders, reshaping the adjacent severed ends of said lead-in wires to form spaced filament connection portions, mounting a filament on the said filament connection portions of said lead-in wires to form a lamp mount, repositioning the envelope and said holders relative to one another to locate the said lamp mount in sealing position within the envelope, fusing and sealing one of the open ends of the said envelope around the respective lead-in wire positioned therewith, flushing the interior of said envelope with a stream of inert gas directed thereinto from within its open other end, and then fusing and sealing the said, other end of the envelopearound the respective lead-in wire positioned therewithin.

9. The method of making an electric incandescent lamp comprising the steps of inserting a lead-in wire holder through a glass lamp envelope through openings in opposite ends thereof, feeding a length of 'wire from a continuous supply thereof and clamping it between the through-insertedend of said holder and a second holder located exteriorly of said envelope, severing the said length of Wire from the remainder of the said supply thereof and cutting it in two at a region between the said holders to form two separate lead-in wires held in the respective holders, reshaping the adjacent severed ends of said lead-in wires to form spaced filament clamping hooks thereon, clamping a filament in the said hooks on the lead-in wires to form a lamp mount, repositioning the envelope and said holders relative to one another to locate the said lamp mount in sealing position within the envelope, and then sealing the said lamp mount into the opposite ends of the envelope.

10. The method of making an electric incandescent lamp comprising the steps of inserting a lead-in wire holder through a glass lamp envelope through openings in opposite ends thereof, feeding a length of wire from a continuous supply thereof and clamping it between the through-inserted end of said holder and a second holder located exteriorly of said envelope, severing the said length of wire from the remainder of the said supply thereof and cutting it in two at a region between the said holders to form two separate lead-in Wires held in the respective holders, reshaping the adjacent severed ends of said lead-in Wires to form spaced filament clamping hooks thereon, clamping a filament in the said hooks on the lead-in wires to form a lamp mount, repositioning the envelope and said holders relative to one another to locate the said lamp mount in sealing position within the envelope, fusing and sealing one of the open ends of said envelope around the respective lead-in wire positioned therewithin, flushing the interior of said envelope with a stream of inert gas directed thereinto from within its open other end, and then fusing and sealing the said other end of the envelope around the respective lead-in wire positioned therewithin.

References Cited by the Examiner FOREIGN PATENTS 432,879 8/ 1926 Germany.

FRANK E. BAILEY, Primary Examiner.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
DE432879C *Aug 16, 1926Patra Patent TreuhandVerfahren und Anordnung zur Herstellung von Stromzufuehrungsdraehten fuer elektrische Gluehlampen
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3736630 *Jul 31, 1969Jun 5, 1973Field MApparatus and methods for making miniature incandescent lamps and the like
US3791710 *Mar 24, 1972Feb 12, 1974Wagner Electric CorpMethod for producing a multiple filamented cartridge lamp
US4389201 *Feb 5, 1981Jun 21, 1983General Electric CompanyMethod of manufacturing a lamp
US5209689 *Dec 27, 1991May 11, 1993Gte Products CorporationMethods for mounting filaments in tubular incandescent lamp capsules
US5213536 *Jan 2, 1991May 25, 1993Gte Products CorporationFilamented lamp manufacture method
Classifications
U.S. Classification445/27, 445/40, 445/32, 140/71.6
International ClassificationH01K3/00
Cooperative ClassificationH01K3/00
European ClassificationH01K3/00