US3441776A - Filament support for incandescent electric lamps - Google Patents

Description

P 1969 J. s. CARDWELL, JR 3,441,776

FILAMENT SUPPORT FOR INGANDESCENT ELECTRIC LAMPS Filed May 12, 1967 lnvenfitor": John G. Car'dwetl dr. 109 0x2; JZ

His A't to e9 United States Patent Office 3,441,776 Patented Apr. 29, 1969 US. Cl. 313-273 2 Claims ABSTRACT OF THE DISCLOSURE In a single-ended incandescent electric lamp, particularly of the high intensity halogen regenerative cycle type, comprising a sealed envelope of vitreous material containing a coiled filament and having a pinch seal at one end and a pair of lead-in conductors having portions thereof hermetically sealed in said pinch seal, the coiled filament is composed of sections which extend in generally side-by-side relation longitudinally of the envelope with their lower ends electrically connected to the lead-in conductors. The sections of the filament are physically separate segments, and their upper ends are supported by, and electrically connected together by, a support member preferably in the shape of an inverted double-J consisting of a length of wire formed as I-shaped wire sections arranged back-to-back. The stem portion of the double-J extends longitudinally between the filament segments, has its lower end embedded in the pinch seal, and has its upper hookshaped ends fitted or threaded a supporting mandrels Within the interior of respective helically coiled upper end portions of the respective filament sections.

BACKGROUND OF THE INVENTION Field of the invention This invention relates generally to electric incandescent lamps comprising a sealed bulb or envelope containing a filament, and more particularly to a filament support structure.

Description of the prior art The invention relates more particularly to lamps of a single-ended type comprising a sealed envelope having a pinch seal at one end thereof, a pair of lead-in conductors having portions thereof hermetically sealed in said pinch seal, and a coiled filament formed to provide sections which extend in generally side-by-side relation, for example a generally U-shaped or V-shaped filament having its ends supported from the pinch seal and electrically connected to respective lead-in conductors. Still more par ticularly, the invention relates to such lamps wherein it is required that the filament be provided with supplemental support means at its midpoint or apex. In some such cases the support has been provided by a wire having one end looped about the filament and its other end secured or sealed in an exhaust tip at the end of the envelope opposite the pinch seal. In another case the support wire was in the form of an inverted hairpin or U having its ends embedded in the pinch seal and having a loop at its bend enclosing the filament at its apex. Such prior art structures present certain problems in difficulty of assembly and proper location or orientation of the support members and filaments.

SUMMARY OF THE INVENTION In accordance with the present invention, the filament is formed of physically separate sections, and the support wire member is formed to provide a stem portion having one end thereof sealed in the pinch seal between the lead-in conductors and extending therefrom longitudinally into the interior of the envelope where it terminates in branches extending short distances laterally of the stem portion in opposite directions. The separate filament sec tions are arranged to extend generally longitudinally of the envelope at opposite sides of the stem portion of the support member with helically coiled end portions thereof threaded over respective said branches as supporting mandrels therefor; the opposite ends of the filament are electrically connected to respective lead-in conductors. In a preferred form, the support member is of generally doubleshape formed of a length of wire which is doubled back upon itself to constitute the stem portion and which has its free ends formed as hooks arranged in back-to-back relation in a common plane. Such an arrangement of filament and support member is readily assembled with the parts in proper relationship, as will more clearly appear from the following detailed description and from the drawing.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is an elevation of a lamp comprising the invention;

FIG. 2 is an exploded elevation, on an enlarged scale, showing the parts of the filament and support members prior to assembly;

FIG, 3 is an exploded elevation showing the filament and support wire elements in assembled relationship, and a pair of lead-in conductors prior to assembly with the filament;

FIG. 4 is an elevation showing the assembly of the complete filament mount structure held in a supporting fixture, and a bulb or envelope held in enclosing relationship to the filament mount for sealing thereto;

FIG. 5 is a top view of the assembly of filament and support wire members shown in FIG. 3;

FIG. 6 is a section through the pinch seal along the line 6-6 in FIG. 1;

FIGS. 7, 8 and 9 are elevations of modified embodiments or species of the filament support wire member;

and

FIG. 10 is a top view of the species of support member shown in FIG. 9.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1 of the drawing, the lamp illustrated therein is of a high intensity regenerative cycle type comprising a compact bulb or envelope 1 of vitreous material of high melting point, preferably essentially fused silica, having at one end thereof a flattened pinch seal 2 which may be of known I-shaped cross section (FIG. 6) and into which extend a pair of lead-in conductors 3 having thin foil portions 4, preferably of molybdenum, hermetically sealed in the pinch seal 2. The envelope 1 contains a filament, preferably of tungsten, formed to provide sections 5 which extend in generally side-by-side relation with their lower ends supported from the pinch seal 2 and electrically connected to respective lead-in conductors 3, 4. The upper ends of the filament sections 5 are supported by a support wire member 6 which has its lower end embedded and anchored in the pinch seal 2. The envelope 1 also contains a filling of inert gas, such as nitrogen, argon, krypton or xenon and a quantity of halogen, such as iodine or bromine preferably in the form of a compound such as hydrogen bromide or a hydrocarbon of bromide, which functions in known manner as a regenerative getter to return vaporized tungsten to the filament.

In accordance with the invention, as shown in FIG. 2, the filament sections 5 are made as physically separate segments. In this case, each segment is in the form of a helically coiled-coil having upper and lower single coiled end legs 7 and 8 which extend longitudinally therefrom. The legs 7 and 8 are preferably in longitudinal alignment and extend from the edges of the cylinders defined by the respective coiled-coil body portions of the filament 5. The support member 6 is preferably of generally double-J shape formed of a single length of wire, preferably tungsten, which is doubled back upon itself to constitute a stem portion 9 and which has its free ends formed as hooks 10 which extend laterally of the stem portion 9 in opposite directions to be in a common plane. Preferably, there are also provided a pair of spuds or inner lead wire sections 11 which are fitted as mandrels into the interior of the lower filament legs 8.

As shown in FIG. 3, the filament sections are assembled with the support member 6 by threading or fitting the leg portions 7 of the filament over respective hooks as supporting mandrels. The assembled is preferably arranged as shown in FIG. 5 so that the stem 9, hooks 10 and the axes 12 of the coiled-coil filaments 5 lie in a common plane, with the said axes 12 at the outside of the hooks 10. Also shown in FIG. 3 is the remainder of the mount structure consisting of the outer lead wires 3 and foil portions 4 of the lead-in conductors.

As shown in FIG. 4, the outer lead wires 3, carrying the foils 4, are inserted in elongated holes or bores in a supporting block or fixture 13 where they may be securely held by any suitable frictional arrangement which is herein illustrated as a pair of screws 14, and the ends of the lower filament legs 8, with spuds 11 (FIG. 2) held therein, are welded to respective foils 4, preferably through the intermediary of a tab 15 of suitable metal, such as platinum-coated molybdenum, which serves to improve the strength of the weld between the molybde num foil 4 and the tungsten filament leg 8 and spud 11. The stem portion 9 of the support member 6 is quite firmly held in parallel alignment with and between the filament coil sections 5.

As also shown in FIG. 4, the filament mount is enclosed within a bulb or envelope 1 which may be of generally spherical shape with a cylindrical neck portion 17 enclosing the foils 4 and adjacent portions of the filament legs 8 and outer lead wires 3. The bulb is also provided with a tubulation 18 which may be engaged by a pair of jaws indicated at 19, to support the envelope in proper sealing relation to the filament mount structure. The said neck portion 17 of the bulb is then heated to a plastic condition and pinched by a pair of jaws in known manner to form the flattened pinch seal 2 (FIGS. 1 and 6) in which the foils 4 are hermetically sealed and the lower end of the stem portion 9 of the support wire member 6 is sealed and anchored to thereafter firmly support the filament sections 5 at their upper ends.

The bulb 1 is then exhausted or purged of air and filled with an inert gas and a quantity of halogen as well known in the art, and the exhaust tube 18 is sealed or tipped olf as illustrated in FIG. 1.

By way of example only, a lamp as described above may be made to have a rating of some 650 watts at 220 volts in a bulb 1 of essentially fused silica, such as quartz glass or the 96% silica product known as Vycor, and having a diameter of approximately inch, and containing about 800 torr of nitrogen with about 2% by volume of hydrogen bromide.

The modified support wire member 6a shown in FIG.

7 is essentially like that described above and shown in FIGS. 1 to 5. In this case the stem portion 9a is a single length of wire having one of the hooks 10a formed at its upper end, the other hook 10a being formed of a separate piece of wire which is suitably secured, as by welding, to the main stem portion 9a.

In FIG. 8, the support member 6b is of T-shape comprising an elongated stem portion 9b which has welded to its upper end a cross piece forming the opposed branches 10b onto which are threaded the leg portions 7b of the filament sections 5b.

The species of support wire member 66 shown in FIGS. 9 and 10 has a stem portion and hook portions like those described above and shown in FIGS. 1 to 5, but the hooks 10c terminate in lateral extensions 20 which carry pigtail loops 21 each of which is formed as a partial turn of a helix having a diameter and pitch corresponding to part of one secondary coil turn of the coiledcoil filament sections 50. In this case the filament legs 7 of FIG. 2 are omitted, and the primary coiling of part of the uppermost secondary turn of each of the filament sections 50 is threaded over the loop 21 which serves as a supporting mandrel.

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

1. An electric incandescent lamp of the halogen regenerative cycle type comprising a compact sealed envelope of essentially fused silica having a pinch seal at one end, a pair of lead-in conductors extending into said pinch seal from the exterior thereof and including thin foil portions hermetically sealed therein, a filament support wire member of generally double-J shape formed of a length of wire which is doubled back upon itself to constitute a stem portion and which has its free ends formed as hooks arranged back-to-back, said stem portion having its closed end sealed in said pinch seal between said leadin conductors and extending therefrom longitudinally into the interior of said envelope, a filament composed of physically separate helically coiled-coil sections which extend longitudinally of the envelope at opposite sides of the stem portion of said support wire member and which have proximate ends terminating in helically single-coiled legs which are threaded over and snugly enclose respective said hooks as supporting mandrels therefor, and means electrically connecting the opposite ends of said filament sections to respective said lead-in conductors.

2. A lamp as set forth in claim 1 wherein said coiled legs extend from the edges of cylinders defined by respective said coiled-coil sections, and said hooks along with the axes of said coiled-coil sections lie in a common plane, with said axes at the outside of said hooks.

References Cited UNITED STATES PATENTS 2,007,922 7/1935 Braselton 313-273 X 2,007,933 7/ 1935 Braselton 313-344 X 3,194,999 7/1965 Heinlein 313-273 X 3,270,238 8/1966 Mosby 313-279 JAMES W. LAWRENCE, Primary Examiner.

R. F. HOSSFELD, Assistant Examiner.

U.S. C1. X.R. 313-222, 279, 344

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