US2863082A - Electric incandescent lamp - Google Patents

Description

Dec. 2, 1958 F. s. LAMB 2,863,082

ELECTRIC INCANDESCENT LAMP 7 Filed Spt. 24. 1956 Invervtrcr: FT'ech ic| S. Lamb,

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United States Patent O ELECTRIC IN CAN DESCENT LAMP Frederick S. Lamb, Cleveland Heights, Ohio, assignor to General Electric Company, a corporation of New York Application September 24,1956, Serial No. 611,577

4 Claims. (Cl. 313-278) My invention relates to electric incandescent lamps generally, and more particularly to lamps or similar devices having a linear incandescible filament which is required to be maintained under tension.

Various arrangements have heretofore been proposed for maintaining tension on elongated filaments to preserve the linearity of the filament upon expansion thereof when heated to incandescence. However, in many cases the filament is free to vibrate laterally of its length thereby increasing the apparent size or thickness of the light source or even resulting in breakage of the filament.

It is an object of my invention to provide a simple but effective means which will materially minimize lateral vibration of the filament and will also rapidly dampen such vibration. It is a further object to minimize such vibrations without impairing the longitudinal tension on the filament and without providing a sliding engagement with the filament such as would lead to mechanical abrasion.

Briefly stated, these objects are attained by employing an arcuate or loop-shaped flexible spring member located in a plane approximately transverse to the length of the filament and having its ends fixedly secured to spaced points on the filament supporting structure and connected at approximately its midpoint to an end of the filament whereby to resist lateral movement of the filament but allow longitudinal expansion and contraction thereof. The invention will be better understood by reference to the following detailed description and the drawing wherein:

Fig. 1 is a perspective view of an incandescent lamp embodying the invention;

Fig. 2 is a fragmentary elevation showing the spring arrangement for providing tension on the filament and minimizing lateral vibration; and

Fig. 3 is a perspective view of a modified lamp structure embodying the invention.

Referring to Fig. l of the drawing, the lamp illustrated therein comprises an elongated tubular glass bulb or envelope 1 having a base 2 at one end thereof. The end of the bulb is provided with a conventional re-entrant stem 3 through which extends a pair of rigid lead-in conductors 4 and 5. The conductor 4 extends a short distance into the bulb whereas the longer conductor or stay member 5 extends substantially the fulllength of the bulb to its remote end and is rigidly maintained in a fixed position by one or more transverse brace members 6. As herein illustrated, the brace members are in the form of heavy wire loops engaging the wall of the bulb and welded to the conductor 5, one at the remote end of the bulb and another adjacent the proximate end of the bulb near the stem 3. In some cases the brace 6 adjacent the stem 3 may be omitted, par- 'At its remote end the filament is secured to a short length of lead wire 8 and is maintained under tension by suitable flexible spring means. As herein illustrated, the tension springs each consist of a closely coiled helix of tungsten-wire 9 secured fixedly at one end to the conductor 5 and at the other end to the lead wire 8. Since the springs 9 are in the electrical circuit through the filament '7 and conductor 5 they are made of wire of a size sutficient to prevent overheating upon flow of current therethrough so as to maintain their resilience. In the cold or contracted position of the filament the springs 9 are bent back to a reverse curvature so as to exert tension on the filament even in its expanded position.

As thus far described the filament 7 is adequately maintained under tension. However, because of the long unsupported length of the filament and its small diameter (.002 inch for instance) the filament is free to vibrate at right angles to its length, that is, normal to the plane containing the filament 7, conductor 5' and springs 9. According to the present invention, such vibration is materially minimized and effectively dampened by the provision of a supplementary vibration spring member 10 connecting two points on the filament supporting structure with the end of the filament. The

. spring 10 is a flexible wire member bent to an arcuate ticularly when the lamp is of relatively short length; on

the other hand, additional intermediate braces may be employed in lamps of longer length.

A filament 7 of straight tungsten wire is secured at one end to an end of the shorter lead-in conductor 4.

or openloop form having its ends secured fixedly by welding to spaced points on the adjacent brace 6 and connected approximately at its midpoint to the end of the filament through the lead wire 8 to which the spring is fixedly secured, preferably by welding. The spring 10 is thus locatedapproximately in a plane transverse to the length of the filament 7, As shown more clearly in Fig. 2 the said spring 10 is preferably bent back similarly to the springs 9 so it also exerts tension on the filament. t i

In a preferred construction the spring 10 is a helical coil'of tungsten wire like the springs 9. However, each of the springs 10 and 9 may alternately be constituted of a bundle of fine tungsten wires, for example, about twenty-five strands of 6 mil wire.

When the lamp is subjected to shock or impact tending to cause the filament 7 to vibrate laterally of the plane.

including the filament and the springs 9, such vibration is minimized and is rapidly dampened by the flexible spring 10. It will be apparent that this effect is obtained without adverse interference with the tensioning effect of the springs 9 and without the presence of any sliding contact with the filament such as would lead to abrasion. While the spring 10 resists lateral vibration of the filament, it allows longitudinal movement thereof. In fact, as mentioned above, it is preferably so mounted that it supplements the tension exerted by the springs 9 so that in some cases, as when the filament 7 is of comparatively short length, the springs 9 may be omitted and one or more springs 10 may be employed to supply all the longitudinal tension on the filament as well as the anti-vibration function.

The modified form of lamp shown in Fig. 3 is essentially like that shown in Fig. 1 except that the spring arrangement is located at the opposite or base end of the lamp. Accordingly, the filament 7 is fixedly secured at the remote end of the lamp to a short length of conductor 11 which constitutes an extension of the conductor 5. The

proximate end of the filament is attached to the short sion of the filament 7, it may be resiliently supportedat *bot-h'ends -by combining the spring arrangements shown in -Figs. 1 and -3. It will "also be apparent to those skilled in the art that various other modifications, substitutions or omissions may be made within the scope of 'the-inventionwhileretaining the features and functions of the vibration spring 10.

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

1. An electric incandescent lamp comprising an elongated sealed bulb, a filament extending'longitudinally of said bulb,-and support means for said filament comprisingmeans to maintainlongitudinal tension on the filament and to minimize lateral vibration and including a fiexible spring member bent to arcuate form and located in a plane substantially transverse to the filament and having its ends secured fixedlyto portions of said supporting means, and means fixedly connecting the spring member at approximately its midpoint to one end of the filament whereby to dampen vibration of said filament in directions transversely of its length while allowing longitudinal expansion and contraction of the filament.

2. An electric incandescent lamp comprising an elongated sealed bulb, a filament extending longitudinally of said bulb, and support means for said filament comprising-means to maintain'lo-ngitudinal tension on the filament and to minimize lateral vibration and including a helically coiled flexible spring member bent to arcuate form and located in a plane substantially transverse to the filament and having its ends secured fixedly to portions of said supporting means, and means fixedly connecting the spring member at approximately its midpoint to one end of the filament whereby to dampen vibration of said filament in directions transversely of its length while allowing longitudinal expansion and contraction of the filament.

3. An electric incandescent lamp comprising an elongated sealed bulb, a filament extending longitudinally of said bulb, support means for said filament comprising a stay member extending longitudinally of the bulb and a brace member secured to said stay member and extending laterally therefrom into engagement with said bulb and means for resiliently supporting said filanentunder tension from-said supportmeans and including a flexible spring member bent to arcuate form and located-in'a-plane-substantially transverse to the filament and having its ends secured fixedly to spaced portions of said brace member, and means fixedly connecting said spring member at approximately its midpoint to one end of the filament whereby to dampen vibration of said filament in directions transversely of its length while allowing longitudinal expansion and contractions of the filament.

4. An electric incandescent lamp comprising an elongated sealed bulb, a filament extending longitudinally of said bulb, support means for said filament comprising a stay member extending longitudinally of the bulb and a brace member secured to said stay member and extending laterally therefrom into engagement with said bulb and means for resiliently supporting said filament under tension from said support means including a plurality of flexible tension spring members extending laterally of the bulb and fixedly connected at respective ends to an adjacent end of the filament and to said stay member adjacent said brace member, said tension spring members being flexible in directions both within and transversely of the plane including said filament and tension spring members, and a helically coiledvibration spring member bent to form an open loop located in a plane substantially transverse to the filament and having its-ends secured fixedly to spaced'portions of said brace member, and means fixedly connecting said vibration spring member at approximately its midpoint to the adjacent end of the filament whereby to dampen transverse vibration of said filament.

References Cited in the file of this patent UNITED STATES PATENTS 1,800,037 Wiegand Apr. 7, 1931 2,145,912 Anderson Feb. 7, 1939 2,425,864 Cartun Apr. 19, 1947 2,425,865 Cartun Apr. 19, 1947 2,467,710 Vanttorn et al Aug. 19, 1949 2,565,138 Leighton Aug. 21, 1951

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