US3496403A

US3496403A - Single-ended electric incandescent lamp and mount assembly therefor

Info

Publication number: US3496403A
Application number: US716822A
Authority: US
Inventors: James J Palermo; Arthur A Bottone
Original assignee: Westinghouse Electric Corp
Current assignee: Philips North America LLC
Priority date: 1968-03-28
Filing date: 1968-03-28
Publication date: 1970-02-17
Anticipated expiration: 1987-02-17

Description

. J.J. PALERMo Erm. SINGLE-ENDED ELECTRIC INCANDESCENT LAMP Feb. 17, 1970 AND MOUNT ASSEMBLY TnEnEFoR Filed March 28 INVENTORS James J Polermo 8 Arthur A. Bottone.

I/llll I l rl/I I 4 wlrNEssEs:

United States Patent O 3,496,403 SINGLE-ENDED ELECTRIC INCANDESCENT LAMP AND MOUNT ASSEMBLY THEREFOR James J. Palermo, Methuen, Mass., and Arthur A.

Bottone, South Amboy, NJ., assignors to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Mar. 28, 1968, Ser. No. 716,822 Int. Cl. H01k 1/18; H013 1/88, 19/42 U.S. Cl. 313-222 12 Claims ABSTRACT F THE DISCLOSURE A compact halogen-containing incandescent lamp having a multi-section coiled-coil filament that is suspended within the lamp envelope by a lcompressible wire support ring which is seated within a circumferential recess formed in the envelope wall. The support ring has a laterally extending hooked portion that is coupled to a medial segment of the filament located between the coiled-coil sections. The opposite ends of the coiled-coil sections of the filament are fastened to rigid lead-in conductors that extend through a press seal and are electrically connected to pin contacts carried by a base member attached to the press seal.

BACKGROUND OF THE INVENTION This invention relates to electric incandescent lamps and has particular reference to an improved halogen-containing projection lamp and a filament mount assembly for such a lamp.

Compact so-called halogen cycle incandescent lamps are well known in the art. Lamps of this type are more efficient and have a longer life than conventional incandescent lamps in that the iodine or bromine atmosphere that is commonly used establishes a gettering cycle that returns vaporized tungsten to the filament and markedly reduces the bulb blackening that would otherwise occur. Such halogen type lamps are thus admirably suited for use in film projectors and the like where a compact highly-efficient light source would permit the size of the projector to be decreased without sacrificing picture brightness.

In order to concentrate as much of the light as possible at the film gate of the projector, it is the common practice to use coiled-coil filaments having a plurality of sections that extend longitudinally of the envelope and are disposed in side-by-side relationship. Prior art projection lamps of this type have presented a problem in that a support wire, or other suitable support means, which extends along and to one side of the filament is required to hold the filament in the proper upright position within the envelope. Mounts having such longitudinally-extending filament support structures are not only difficult and expensive to fabricate and assemble but reduce the usable light output of the lamp since the support structure blocks light rays that would otherwise pass directly out of the lamp into the optical system of the projector, or light rays that would be redirected into the optical system by the reflector located behind the lamp.

SUMMARY It is accordingly the general object of the present invention to provide a compact incandescent lamp having a concentrated filament that is supported in a predetermined position within the lamp envelope by means which can Abe conveniently and inexpensively fabricated and which will not impair the effective light output or efficiency of the lamp.

A more specific object is the provision of a single-ended halogen-cycle projection lamp having a multi-section 3,496,403 Patented Feb. 17, 1970 coiled-coil filament that is precisely oriented within the lamp and is held in such position without obstructing light that would otherwise enter the optical system of the projector.

Another object is the provision of a filament mount assembly for a single-ended electric incandescent lamp that permits the filament to be conveniently and accurately suspended within the lamp envelope.

The foregoing objects and other advantages are achieved in accordance with the present invention by supporting the upper end of the filament by means of a compressible member that is seated within a circumferential recess provided in the inner wall of the bulb. Accordingly, to a preferred embodiment, a compressible loop of resilient wire is mechanically locked in an annular groove formed in the bulb Wall near the domed top of the envelope. The loop has a radially extending end portion that is terminated by a hook which supportingly engages the medial segment of a multi-section coiled-coil filament. The filament legs are attached to rigid lead-in wires anchored in a press Seal formed on the opposite end of the envelope so that the filament is suspended in predetermined position within the envelope and the light rays can pass through the side walls of the envelope without being obstructed.

BRIEF DESCRIPTION OF THE DRAWING A better understanding of the invention will be obtained by referring to the accompanying drawing, wherein:

FIGURES 1 and 2 are front and side sectional views, respectively, of a 500` watt halogen-cycle projection lamp incorporating the present invention;

FIG. 3 is an exploded view of the lamp envelope and a filament mount assembly that is ready for insertion into the envelope; and

FIG. 4 is a front sectional view of an alternative lamp embodiment.

DESCRIPTION OF EMBODIMENT I In FIG. 1 there is shown one form of the invention embodied in a 500 watt T6 incandescent projection lamp `10 having a tubular vitreous envelope 12 of circular cross section that is terminated at one end by a rounded dome portion 14 having a protruding sealed-off remnant 16 of a vitreous exhaust tube. The dome portion 14 is joined to the cylindrical body portion 17 of the envelope 12 by a protruding rim or bead 18 that defines an interior circumferentially-extending recess or groove 20 that is disposed in a plane which is substantially normal to the longitudinal axis of the lamp 10. The opposite end of the envelope 12 is closed by a hermetic seal portion 22 which, in the embodiment here shown, constitutes a press seal of I-shaped cross section.

As will be noted in FIG. 2, the sides 19 of the envelope -body portion 17 adjacent the press seal 22 taper inwardly toward and merge with the flat faces of the seal.

In accordance with this embodiment of the invention, a suitable filament 23 of refractory material, such as a multi-section V-shaped coiled-coil (a so-called CCZV) fila-ment of tungsten wire, is centrally suspended within the envelope 12 by means of a compressible support member such as a loop 28 of resilient wire that is seated in the circumferential interior groove 20 and 'is locked in such position solely by the envelope Walls. The bead portion 18 of the envelope 12 is so formed, as shown in FIGS. l and 2, that the domed and body portions of the envelope immediately adjacent the wire loop 28 extend laterally for a short distance and form a pair of spaced annular shelves or seats that tightly lock the Iwire loop in position.

As will be noted more clearly in FIG. 3, the wire loop 28 in the particular embodiment here shown comprises a closed circular ring that has an overlapping arcuate end portion 29 and a radially-extending straight end portion 30 that is terminated by a retroverted bend which constitutes a hook 31. This hook engages the upwardly extending bight 26 of the filament 23 that joins the two coiled-coil sections 24 and thus maintains the filament in the desired suspended position. The hook 31 is located at the center of the wire ring 28 and is thus aligned with the longitudinal axis of the lamp The filament 23 is thus axially aligned with respect to the envelope 12.

Returning to FIGS. l and 2, it will be noted that the lower end of the filament 23 is held in place by attaching the straight leg sections 32 of the respective coiledcoil sections 24 to rigid lead-in conductors 34 that are anchored in the press seal 22. The conductors 34 are, in turn, fastened as by spot welding, to a pair of ribbon conductors 3-6. The ribbons are fastened to a pair of rigid outer lead wires 38 that protrude from the end of the press seal 22 and are electrically connected to a pair of pins 40 anchored in the bottom wall 41 of a hollow-base 42 attached to the press seal by a suitable high-temperature cement 44. Exposed portions of both of the outer leads 38 are of reduced cross section and form fusible elements 46 that protect the lamp from violent failure when the filament 23 fails at the end of life. Only one such integral fuse can be used if desired. The bottom wall 41 of the base 42 defines a fiat registration surface that is disposed in a plane that 'is normal to the longitudinal axis of the lamp 10 and is spaced a predetermined axial distance from the center of the filament 23. The aforesaid registration surface thus determines the critical light-center-length dimension of the lamp and insures that the filament 23 will be accurately positioned relative to the optical axis of the projector when the lamp 10 is seated in its socket.

In the case of a halogen-cycle lamp of the type here shown, the lamp atmosphere preferably consists of bromine or iodinein which case the envelope is made of quartz and the wire ring 28 and inner leads 34 are fabricated from tungsten or other suitable refractory material that will not deleteriously react with the lamp atmosphere.

As will be noted in FIG. 3, the outer diameter of the ring support 28, when in relaxed condition, is slightly larger than the inner diameter of the cylindrical envelope 12. Thus, when the filament mount assembly 48 (consisting of the ring support 28, coupled filament 23 and attached lead-fin conductor assembly comprising the joined inner leads 34, ribbon conductors 36 and outer U-shaped lead member 38') is inserted into the envelope 12 the ring will be constricted slightly and then expand into the groove 20, thus locking the inner end of the mount in the envelope. The mouth of the envelope 12 is press sealed around the ribbons 36 and adjacent portions of the inner leads 34 and outer hairpin-like lead 38', and the latter is severed adajcent the U-bend to provide a pair of exposed leads 38 (FIGS. l and 2) of the proper length. The envelope 12 is then exhausted, filled with nitrogen (or argon, or a mixture of argon and nitrogen), dosed with a predetermined amount of a halogen (or a halogen-forming compound) through the tube 16 and the latter is tipped off.

The use of the hair-pin or U-shaped one-piece lead component 38' is an important feature of the invention since it permits the mount 48 to be made as a separate assembly and inserted into the envelope 12. The use of the ring support 28, iin addition to permitting the filament 23 to be accurately suspended -within the envelope 12, also provides excellent electrical insulation between the mount components since the support 28 and inner leads 34 are located at opposite ends of the envelope.

EMBODIMENT II In FIG. 4 there is shown another lamp embodiment 10a having a different type of filament 50 and a modified wire ring support 28a. The filament 50 comprises a socalled 2CC8 coil of tungsten wire having two

coiledcoil sections

51, 52 that are disposed in parallel side-byside relation and joined by a laterally-extending medial coiled-coil segment 53 consisting of approximately three secondary turns. The radially extending end portion of the ring support 28a is terminated by a shallow U-shaped hook 31a that extends through and shorts out all of the secondary turns of the medial coiled-coil segment 53. Thus, only the parallel-spaced coiled-

coil sections

51, 52 incandesce when the lamp is energized and serve as the light source.

In addition to serving as a point of anchorage for the filament 50, the medial coiled-coil segment 53 provides a resilient floating bridge structure between the

sections

51, 52 that permits them to expand and contract freely as the lamp is turned off and on. Thus, distortion of the

coil sections

51, 52 and variations in inter-coil spacing during the life of the lamp are drastically reduced at no additional cost.

The lamp 10a is the same as lampy 10 as regards the configuration of the envelope 12a, the manner in which the inner leads 34a are supportingly joined to the filament legs 54, 55, the construction of the base 44a, etc.

It will be appreciated from the foregoing that the objects of the invention have been achieved in that an improved single-ended projection lamp has been provided in which a multi-section filament of complex configuration is accurately and securely supported within the envelope without obstructing any usable light rays. An integral mount assembly that can be conveniently and economically manufactured and sealed into the lamp envelope has also been provided.

While several embodiments have been illustrated and described, it will be understood that further modifications can be made without departing from the spirit and scope of the invention. For example, a 2CC8 filament can be used wherein the coiled-coil sections are joined by a singly coiled section of bight instead of the short medial coiledcoil section of a few turns shown in Embodiment II. Of course, the filament can also consist of a length of tungsten wire or other suitable refractory material that is coiled but once.

We claim as our invention:

1. A single-ended electric incandescent lamp comprisa light-transmitting envelope having a sealed portion at one end and a portion at its opposite end that defines an interior circumferential recess,

a filament of refractory material suspended within said envelope, and

means supporting said filament in the aforesaid position comprising (1) a rigid lead-in conductor that is anchored in the sealed portion of said envelope and is fastened to one end of said filament and (2) a compressible member interlockingly seated in said circumferential recess and having a depending element that is coupled to a portion of said filament remote from the said one end thereof.

2. The electric lamp set forth in claim 1 wherein;

the sealed portion of said envelope comprises a press seal,

said lead-in conductor extends through said press seal,

a base member is fastened to said press seal, and

the outer end of said lead-in conductor is electrically connected to a contact carried by said base member.

3. The electric lamp set forth in claim 1 wherein;

said envelope is of tubular configuration,

said compressible member comprises a loop of resilient wire and said depending element comprises one end of said wire,

said filament is composed of refractory metal wire and includes two coiled sections that are disposed in spaced side-by-side relationship,

the depending end of said wire defines a hook that supportingly engages a medial segment of said filament that joins the coiled sections thereof,

said rigid lead-in conductor is fastened to the opposite end of one of the coiled sections of said filament, and

a second rigid lead-in conductor is anchored in the sealed portion of said envelope and is fastened to the adjacent end of the other coiled section of said filament.

4. The electric lamp set forth in claim 3 wherein said filament is of coiled-coil construction and generally V- shaped and the medial segment thereof comprises a singlycoiled bight.

5. The electric lamp set forth in claim 3 wherein;

said filament is of coiled-coil construction and thetwo coiled sections are disposed in parallel-spaced relation,

the medial segment of said filament comprises a third coil section having several secondary turns, and

the hook portion of said wire support loop extends through and short circuits all of the secondary turns of said third coil section.

6. The electric lamp set forth in claim 3 wherein;

said filament, wire loop and lead-in conductors are composed of tungsten, and

said envelope contains a halogen atmosphere.

7. The electric lamp set forth in claim 6 wherein said envelope is composed of quartz and contains an iodine or bromine atmosphere.

8. The electric lamp set forth in claim 3 wherein;

the body portion of said envelope is of tubular configuration and circular cross section, the recess-defining portion of said envelope merges with a closed domed end portion,

said wire loop is of circular configuration and has an outer diameter, when in relaxed condition, that is slightly larger than the inner diameter of the tubular body portion of said envelope, and

the depending end of said wire loop extends radially inward and is terminated by a retroverted bend that is substantially aligned with the longitudinal axis of said envelope and forms said hook.

9. The electric lamp set forth in claim 8` wherein;

the sealed portion of said envelope comprises a press seal, and

the domed end portion of said envelope is terminated by a sealed-off remnant of a vitreous exhaust tubulation.

10. The electric lamp set forth in claim 9 wherein;

said filament is of coiled-coil construction,

a base is cemented to said press seal,

the protruding outer ends of said lead-in conductors are electrically connected to a pair of pin contacts that are anchored in the bottom wall of said base,

a portion of at least one of said lead-n conductors that is located within said base is of reduced diameter and constitutes a fuse element, and

the outer surface of the bottom wall of said base is spaced a predetermined distance from the center of said filament and constitutes a registration surface that controls the orientation of the filament with respect to the socket in which the lamp is used.

11. A mount assembly for an incandescent electric lamp comprising;

a filament of refractory metal wire having a pair of coiled sections that are disposed in spaced side-byside relationship and are joined by a medial segment,

an arcuate loop of resilient wire that is disposed in a plane transverse to the filament axis and has a laterally extending portion which includes a hook that is coupled to the medial segment of said filament, and

a rigid U-shaped lead-in conductor member that eX- tends longitudinally from and has its straight end sections fastened to the ends of the respective coiled sections of said filament.

12. The incandescent electric lamp mount assembly set forth in claim 11 wherein;

said filament is of coiled-coil construction,

said wire loop is of closed circular configuration,

the laterally extending portion of said wire loop extends radially inward to the plane of the loop and is terminated by a retroverted protruding bend that constitutes said hook, and

the ends of the coiled sections of said filament that are fastened to said U-shaped lead-in conductor member are substantially straight.

References Cited UNITED STATES PATENTS 317,633 5/1885 Edison 313-273 1,983,362 12/1934 Geiger et al 313-271 X 3,210,587 10/1965 Vile 313-271 JAMES W. LAWRENCE, Primary Examiner P. C. DEMEO, Assistant Examiner U.S. Cl. X.R.