US3930177A

US3930177A - Single-ended incandescent lamp having a simplified filament-mount

Info

Publication number: US3930177A
Application number: US260084A
Authority: US
Inventors: Jack Martin
Original assignee: Westinghouse Electric Corp
Current assignee: Philips North America LLC
Priority date: 1972-06-06
Filing date: 1972-06-06
Publication date: 1975-12-30
Anticipated expiration: 1992-12-30

Abstract

The coiled-coil filament of a quartz-halogen lamp is provided with a continuously-wound leg at each end and is suspended in coaxial position within the tubular envelope by a pair of lead wires that extend into and are secured directly to said legs. The filament leg at the tipped-off end of the envelope has a bent primary turn that defines an opening in the leg and the associated end of the lead wire is formed into an L-shaped hook that extends through the leg opening and into the hollow tip of the envelope.

Description

United States Patent 11 1 1111 3,930,177

Martin Dec. 30, 1975 [54] SINGLE-ENDED INCANDESCENT LAMP 3,497,753 2/1970 Huston, Jr. 313/274 X HAVING A SIMPLFIED 3,641,386 2/1972 Audesse et a1 313/271 X FlLAMENT-MOUNT Primary ExaminerPaul A. Sacher [75] Inventor: Jack Martin, Paramus, NJ. Attorney Agent, or S Buleza [73] Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa. [57] ABSTRACT [22] Filed: J 6, 1972 The coiled-coil filament of a quartz-halogen lamp is provided with a continuously-wound leg at each end [21] Appl' 260084 and is suspended in coaxial position within the tubular envelope by a pair of lead wires that extend into and 52 U.S. c1. 313/271; 313/279; 313/344 are Seeured directly to said, g The filament leg at 51 1m. (:1. 1101.] 1 15; l-lOlJ 1/88 the pp end of the envelope has a bent P y 58 Field of Search 313/271, 274, 279, 344 turn that defines an Opening in the and the ated end of the lead wire is formed into an L-shaped [56] Referen Cit d hook that extends through the leg opening and into UNITED STATES PATENTS th hOllOW Of the envelope.

3,466,489 9/1969 Audesse et al 313/279 X 4Claims, 8 Drawing Figures U.S. Patent Dec. 30, 1975 FIGBA FIGB C FIG. 6

FIG.5

SINGLE-ENDED INCANDESCENT LAMP HAVING A SIMPLIFIED FILAMENT-MOUNT CROSS-REFERENCES TO RELATED APPLICATIONS None.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to electric incandescent lamps and has particular reference to an improved filamentmount structure for a quartz-halogen type lamp.

2. Description of the Prior Art Halogen type incandescent lamps are well known in the art and are used in various industries and applications where a compact source of light or heat is required. A persistent problem in the manufacture of these lamps is that of connecting the ends of the lead wires to the coiled-coil filament and maintaining the latter in centralized position within the tubular quartz envelope during the life of the lamp.

The prior practice has been to fasten the ends of the lead wires to the filament with so-called button-hook connections which were made by forming a single turn (or a partial turn) on the end of the lead wire and screwing it directly into the secondary turn at the end of the filament barrel. A lamp in which the upper end of a coiled-coil filament is fastened to the long lead wire by a separate spud wire using such a buttonhookjuncture is disclosed in U.S. Pat. No. 3,403,280 issued Sept. 24, I968 to J. G. Cardwell, Jr.

In another prior art lamp the coiled-coil filament was wound in such a way that it was terminated by a singlycoiled leg at each end, which legs were joined to the coiled-coil barrel portion of the filament by uncoiled sections of wire or breaks in the primary winding. The filament thus had a sectionally-wound primary coil instead of one which was continuously-wound. The ends of the lead wires were bent into hooks which were inserted into the coil legs and the end of the longer lead wire was positioned within the hollow seal tip formed on the end of the bulb. A lamp having such a filament and mount structure is disclosed in U.S. Pat. No. 3,466,489 issued Sept. 9, 1969 to E. G. Audesse et al.

While the aforementioned prior art mounts held the filament in the desired coaxial position within the envelope and provided satisfactory electrical connections between the leads and filament, they were complicated and difficult to assemble and required expensive precision-made spud wires or filaments which had uncoiled sections and could thus not be wound continuously. Such filaments, accordingly, had to be wound on machines which provided the desired breaks" or ancoiled sections in the primary coiling and the secondary winding operation then had to be done by a skilled operator in order to insure that the uncoiled sections were positioned at the proper location between the respective coil legs and the ends of the coil barrel. This prevented the filaments from being manufactured on automatic secondary-winding machines and greatly increased the manufacturing cost of both the filaments and lamps.

I SUMMARY OF THE INVENTION The foregoing deficiencies and problems encountered with the prior art filaments and mount structures are overcome in accordance with the present invention by utilizing a coiled-coil filament that initially has a continuously-wound primary winding and, by means of a simple operation, is subsequently modified by bending a primary turn, in such a way that it provides an opening in one of the filament legs which permits the hooked end of the long lead wire to be inserted into the leg, through the opening in the leg, and into the hollow tip of the bulb. In the preferred embodiment the end of the longer lead is bent into an L-shaped hook having an arcuate bend and an upstanding stud segment that projects through the leg opening into the envelope tip and thereby maintains the filament in the desired centralized position within the envelope.

Various alternative embodiments using other kinds of lead hooks and filament legs are also disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of the invention will be obtained from the exemplary embodiments shown in the accompanying drawing, wherein:

FIG. 1 is an elevational view of a 250 watt T4 incandescent lamp embodying the present invention;

FIG. 2 is an enlarged view of the top portion of the mount structure employed in the lamp of FIG. 1;

FIGS. 3a to 30 are views illustrating different stages in the manufacture of the coiled-coil filament according to the invention; and

FIGS. 4 to 6 are elevational views of alternative filament-mount embodiments.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 there is shown a 250 watt single-ended incandescent lamp 10 of the halogen-cycle type which embodies the preferred form of the invention and comprises the usual tubular envelope 12 of quartz (or other suitable high melting point material) that is terminated by a hollow tip 14 and is hermetically closedat its opposite end by a press seal 16 which is cemented to a suitable base 18. The envelope 12 in this particular embodiment is of the T4 type k inch or 12.7 mm OD.) and contains a coiled-coil filament 20 of linear configuration that is wound from a suitable refractory metal wire such as tungsten. The filament 20 is suspended in coaxial position within the envelope 12 by a short lead wire 24 and a long lead wire 25 that are anchored in the press seal 16 and connected to the usual ribbon conductors 17 embedded in the seal.

The coiled-coil filament 20 has a coaxially extending leg 21 that is slipped over and hot clamped to the end of the short lead wire 24 and has a transversely extending leg 22 at its opposite end that has a bent primary turn which defines an opening 23 in the filament leg that is located at the end of the coil barrel.

As will be noted in FIG. 1 and more particularly in FIG. 2, the longer lead wire 25 has its medial portion 26 offset toward the wall of the envelope 12 so that it extends along but is spaced from the filament 20. At a point abreast of the leg opening 23 the long lead wire 25 is provided with a sharp angular bend 27 and the end portion of the lead is formed into a generally L- shaped hook consisting of a transverse arm segment 28 that is joined by an arcuate bend 29 to an upstanding stud segment 30 which projects into the hollow tip 14 of the envelope 12. As shown in FIG. 2, the arcuate bend 29 has a radius of curvature r that is much larger than that of the sharp angular bend 27 and the stud segment 30 is tilted slightly toward the offset medial portion 26 of the lead wire. The radius of curvature r is .at least three times the diameter of the lead wire 25.

This permits the L-shaped hook portion of the longer lead wire 25 to be slipped into the filament leg 22 and and transverse arm segment 28 of the lead wire 25 are of such length that the free end of the leg is seated against. the sharp angular bend 27. The latter thus serves as a stop which automatically positions the filament 20 on the lead wire 25 and'aligns the filament with the envelope axis when the mount assembly is inserted into the envelope and stud segment 30 slips into the bulb tip 14. j v As illustrated in FIG. 1, the rigidity of the mount structure is enhancedby a transverse bridge member 32 of vitreous material that is. fused to the lead wires 24, 25 at a point adjacent the press seal 16. An auxiliary support wire 34 is embedded in the bridge member and coupled by means of a hook toone of the secondary turns of the filament 20. The conjoined filament 20, lead wires 24 and 25, bridge 32, 'and auxiliary support wire 34 thus constitute a unitary mount structure that can be readily handled and sealed within the envelope 12 when: the press seal 16 is subsequently formed.

In the case of a halogen incandescent lamp of the type illustrated, the envelope l2 and bridge 32 are composed of quartz and the lead wire's 24 and 25, the filament 20. and. the auxiliary support wire 34.are all fabricated from tungsten. The envelope is filled with an inert gas such asan argon-nitrogen mixture that is dosedwith a suitable halogen such as iodine or bromine. Of course, the improved mount can also be employed in standardincandescent lamp types that are 1 not dosed with a halogen. I

I :As shown in FIG. 3a, the coiled-coil filament .20 as originally formed has a barrel portion B that "consists of 'aplurality of spaced secondary turns and is terminated at one end by an axially extending leg 21 and at its opposite end by leg 22' that lies perpendicular to the "transverse filament leg 22 is formedby inserting a pointed mandrel-like tool 36 into the leg and manipulating the tool so that its tip permanently deforms and bends a single primary turn from its as-wound" configuration. The tool 38 is then withdrawn. The completed' filament 20 (FIG. 30) thus has a leg 22 of predetermined length with an opening 23 therein that is located at the end of the adjoining secondary turn of the filament. 1 I i To facilitate the turn-bending operationflthe tool 36 should have a diameter that is slightly less than the inner diameter of the primary coil. In the case of the 250 watt T4 lamp illustrated, satisfactory results have been obtained by using a tungsten tool whose diameter was about0.025 mm. smaller than the diameter of the primary mandrel. The lead wire 25 had a diameter of about 0.38 mm. and the radius of curvature r of the arcuatebend 29 was approximately 1.5 mm. or about four times the wire diameter.

As shown in the alternative embodiment depicted in FIG. 4, the turn-bending operation can be performed in such a manner that a longitudinally-extending leg 220 can be provided at the top of the lamp a. In this case, the arcuate bend 29a of the long lead wire 25a extends into the leg opening 23a and the upstanding stud segment 30a of the hooked end of the lead is located within and projects beyond the filament leg 22a into the bulb tip 14a. The arm segment 28a is thus isolated from the filament a and merely serves to maintain the offset medial portion 26a of the lead wire a in the desiredlocation adjacent the envelope wall. Since only the stud segment a extends through the leg 22a in this embodiment, the arcuate bend 29a can have the same radius of curvature as the sharp bend 27a and the stud segment can extend axially and need not be tilted. The other leg-lead wire junction and features of the mount assembly are identical to those shown in FIG. 1 and previously described.

In FIG. 5 there is shown another mount structure that I utilizes a top filament leg-lead wire juncture that is identical to that shown in FIG. 4 but which utilizes a modified juncture between the short lead wire 24b and the bottom leg 21b of the filament 20b. As illustrated,

the'axially-extending leg 21b has a selected primary turn that is bent to provide a leg opening 38 which permits the downwardly-extending tip of a retroverted hook 40 formed on the end of the shortlead 24b to be inserted through the leg opening and into the filament In the embodiment shown in FIG. 6, the top leg-lead wire connection is identical to that shown in FIGS. 1 and 2-and a modified filament leg-lead wire juncture is employed at the opposite end of the filament 200. As will be noted, a selected primary turn of the filament leg 210 at that end of the filament 200 is bent through an angle such that the leg extends transversely with respect to the filament axis and forms a leg opening 42 which permits the tip of a hook 44- provided at the end of the short lead 24c to be slipped into the leg 21c and through the leg opening 42. I claim as my invention: 1. In a single-ended electric incandescent lamp having a tubular envelope that is terminated at one end by a hollow tip and is closed at its other end by a press seal, said hollow tip being substantially aligned with the axis of the envelope, at mount structure comprising;

an elongated coiled-coil filament of continuouslywound refractory metal wire having a singly-coiled leg at each end that constitutes an integral part of the filament as wound and thus consists of a plurality of continuously-wound primary turns, one of i said legs having a primary turn that is bent from its as-wound c'onfiguration'and defines an opening in the leg that is located a predetermined distance from the free end of said leg, and means suspending said coiled=coil filament in longitudinal position within the envelope comprising a pair of rigid lead wires of unequal length that are anchored in said press seal and are secured to the legs of said filament, v

the longer of said pair of lead wires being disposed alongside of but spaced from said filament and being terminated by a generally L=shaped hook portion that extends through the filament leg with the bent primary turn, through the opening in said leg defined by said bent primary turn and into the hollow tip of the envelope,

the part of said longer lead wire that extends alongside the filament being substantially straight, offset toward the envelope wall, and joined to the generally L-shaped hook portion of said longer lead wire by a sharp angular bend, and Y the end of the filament leg which is secured to said longer lead wire being seated against said sharp angular bend so that said bend thus serves as a stop for positioning the filament leg on said longer lead wire.

2. The incandescent lamp of claim 1 wherein;

the generally L-shaped hook portion of said longer lead wire consists of a laterally-extending arm segment and an upstanding stud segment that is joined to said arm segment by an arcuate bend which has radius of curvature at least three times the diameter of said longer lead wire,

the opening in the associated filament leg defined by the bent primary turn is located adjacent the end of the coiled-coil barrel portion of the filament and said leg extends transversely relative to the filament axis,

the arm segment of said longer lead wire is disposed within said transversely-extending leg of the filament and the arcuate bend of said lead wire extends through the opening in said filament leg, and

said filament leg and the arm segment of said longer lead wire are of such length that the associated end of the suspended filament is disposed in substantially coaxial relationship with the envelope.

3. The incandescent lamp of claim 2 wherein;

the other leg of said filament is disposed in substantially coaxial relationship with the filament, and

the end of the short lead wire extends along the envelope axis and into said coaxially-disposed leg so that the filament is centrally positioned in the envelope.

4. The incandescent lamp of claim 3 wherein;

said coiled-coilfilament andpair of lead wires are composed of tungsten,

a transverse bridge member is secured to said lead wires at a location adjacent the press sealed end of the envelope,

said bridge member and envelope are composed of quartz, and

said envelope contains an atmosphere consisting essentially of an inert fill gas and an admixed halogen.

Claims

1. In a single-ended electric incandescent lamp having a tubular envelope that is terminated at one end by a hollow tip and is closed at its other end by a press seal, said hollow tip being substantially aligned with the axis of the envelope, a mount structure comprising; an elongated coiled-coil filament of continuously-wound refractory metal wire having a singly-coiled leg at each end that constitutes an integral part of the filament as wound and thus consists of a plurality of continuously-wound primary turns, one of said legs having a primary turn that is bent from its as-wound configuration and defines an opening in the leg that is located a predetermined distance from the free end of said leg, and means suspending said coiled-coil filament in longitudinal position within the envelope comprising a pair of rigid lead wires of unequal length that are anchored in said press seal and are secured to the legs of said filament, the longer of said pair of lead wires being disposed alongside of but spaced from said filament and being terminated by a generally L-shaped hook portion that extends through the filament leg with the bent primary turn, through the opening in said leg defined by said bent primary turn and into the hollow tip of the envelope, the part of said longer lead wire that extends alongside the filament being substantially straight, offset toward the envelope wall, and joined to the generally L-shaped hook portion of said longer lead wire by a sharp angular bend, and the end of the filament leg which is secured to said longer lead wire being seated against said sharp angular bend so that said bend thus serves as a stop for positioning the filament leg on said longer lead wire.

2. The incandescent lamp of claim 1 wherein; the generally L-shaped hook portion of said longer lead wire consists of a laterally-extending arm segment and an upstanding stud segment that is joined to said arm segment by an arcuate bend which has radius of curvature at least three times the diameter of said longer lead wire, the opening in the associated filament leg defined by the bent primary turn is located adjacent the end of the coiled-coil barrel portion of the filament and said leg extends transversely relative to the filament axis, the arm segment of said longer lead Wire is disposed within said transversely-extending leg of the filament and the arcuate bend of said lead wire extends through the opening in said filament leg, and said filament leg and the arm segment of said longer lead wire are of such length that the associated end of the suspended filament is disposed in substantially coaxial relationship with the envelope.

3. The incandescent lamp of claim 2 wherein; the other leg of said filament is disposed in substantially coaxial relationship with the filament, and the end of the short lead wire extends along the envelope axis and into said coaxially-disposed leg so that the filament is centrally positioned in the envelope.

4. The incandescent lamp of claim 3 wherein; said coiled-coil filament and pair of lead wires are composed of tungsten, a transverse bridge member is secured to said lead wires at a location adjacent the press sealed end of the envelope, said bridge member and envelope are composed of quartz, and said envelope contains an atmosphere consisting essentially of an inert fill gas and an admixed halogen.