US2453986A - Circular electric lamp - Google Patents

Description

' Now, 16,, 948. AJGREINER ETAL 2,453,986

cxncumn ELECTRIC LAMP Filed May 7, 1945 AL FRED ERMA/m AUGUST W 55/72 5) W THE/F ATTU/QNE) Patented Nov. 16, 1948 CIRCULAR ELECTRIC LAMP Alfred Greiner, Cleveland Heights, and August W. Seitz, Euclid, Ohio, assignors to'General Electric .Company, a corporation of New York Application May 7, 1945, Serial No. 592,478

1 Claim. 1

This invention relates to electric lamps and discharge devices of a type comprising long envelopes formed in a bent and more or loss nearly closed configuration, which are commonly made of vitreous materials, usually glass. A tubular envelope bent to a circular outline is a representative and very desirable form. The translation means for converting electrical energy into useful radiation in such lamps may be of incandescent filament type, or many involve an electric discharge, or may be of any other suitable kind. The present invention is especially concerned with the basing of these circular or closed figure lamps.

The particular lamp here illustrated and described as an embodiment of the invention is a low pressure positive column fluorescent tube of the general type disclosed in U. S. Patent No. 2,339,166 to Harrison, and the base here illustrated is likewise of the general type shown in that patent. Various novel features and advantages of our invention will appear from the following description of species and forms of embodiment, and from the drawings.

In the drawings, Fig. 1 is a tilted or perspective broken view of a circular lamp tube conveniently embodying the invention, also showing a cooperating connector; Fig. 2 is a side view of one end of the lamp tube on a larger scale, showing an attached part in axial section; Fig. 3 is a fragmentary view of the ends of the lamp envelope associated with part of the base, one end of the envelope being shown in vertical mid-section, and a part of the base being shown detached and reversed in order to reveal its internal conformation; Fig. 4 is atilted view of the base by itself, and Fig. 5 an end view; Fig. 6 is an end view of part of the base in association with an end disc for a lamp, illustrating a modification; and Fig. 7 shows a section through one end of the base taken as indicated by the line and arrows 'I in Fig. 3, and illustrates another modification.

As shown in Fig. 1, the lamp comprises a tubular glass envelope 8 bent to a circular outline and having closed ends 2, 2 directed toward one another, though somewhat spaced, apart. As shown in Figs'. 2 and 3, the tube ends 2, 2 are reduced in size at 3, 3, as is usual for fluorescent tubes, and to these reduced tube ends 3, 3 are attached end disc members 6, 4, at least as large as these ends 3, 3 and here shown of substantially the same external diameter as the ends. Thus the peripheries of the discs 4, 4 present annular shoulders clrcumferentially exposed beyond the glass tube ends 3, 3. Like the discs shown in U. S. Patents Nos. 2,154,550 to White and Johnson and 2,146,579 to Inman, the discs 4, 4 may be of sheet metal (such as the chrome iron known commercially as Allegany to which the glass of the abutting tube ends 3, 3 readily seals by fusion. Whether embossed or dished outward as in Fig. 2, or flat as in Fig. 3, the discs 4, 4 may be stiffened with marginal flanges 5, 5, to the inside of which the glass may also be fused. Instead, however, 01' having an inward projecting boss as in the last-cited patents, each disc rl has an outward projecting conically enlarged boss 6 which is centrally apertured at I; or, to state it differently, the disc has an outwardprojecting and flaring flange around an aperture 8 with an inturned edge 9 defining the bossaperture I. The bosses or flanges 6, 6 may be utilized as annular shoulders to engage in and center a common base I0 for the tube ends 3, 3, Fig. 3, as hereinafter more particularly described; moreoYer, their undercut or overhanging shoulder conformation as described affords a grip by which the ends of an initially straight tube I can be held to bend it to the desired circular or closed configuration after it has been softened by heat, all as described in our applicationSerial No. 574,724, filed January 26, 1945.

As shown in Fig. 3, the electrode mounts ll, ll of the lamp 1 may be of ordinary stem and flare type, sealed in, preferably, concurrently with the attachment of the discs 4, t. The electrodes of these mounts I l, l I may be of any well-known or preferred type, whether for hot-starting after a period of cathode preheat, as exemplified in U. S. Patents Nos. 2,29,203 to Peters, 2,330,161 to Townsend and 2,306,925 to Aicher or for "coldstarting without such preheat, as also disclosed in said Aicher patent, As here illustrated, each mount ll comprises a thermionic cathode l2 0i coiled or coiled-coil tungsten filament type, preferably coated and activated with charges of alkaline earth metal oxide(s) such as a mixture including barium and strontium oxides. The mount l i may also include the usual unemissive auxiliary anodes. The current connections or leads l3, It

for the electrode are sealed and extend out through the stem flare ll, which as here shown escapee closes oil the end of the envelope I. An inner exhaust tube I4 opening through the seal is shown as also extending out through the stem, and as sealedoff at II. The envelope I may contain a low-pressure atmosphere of starting gas, such as argon at a pressure of 2 to 6 mm. of mercury, more or less, and also a vaporizable and ionizable working substance such as mercury. A supply of mercury, which may exceed the amount that will vaporize during operation of the lamp, is indicated by a drop I6 inside the envelope I, and an internal coating of fluorescent material or phosphor I! on the envelope walls is also indicated.

As shown in Figs. 3, 4, and 5, the lamp base structure III common to the tube ends 3, 3 is hollowed (at least at its ends) to engage around and fit the circumferential shoulders afforded by the discs 4, 4 as above described. As shown in Fig. 3, each end of the base III has a double shouldered engagement with the corresponding disc 4: at I8 around the disc periphery, and at I9 around the periphery of the boss or flange 6. However, such double engagement-is not always necessary, since either shouldered engagement sufhces to hold the base IIi'in position. The base I may be hollowed throughout its axial length to afford an ample internal cavity for passage of the lamp leads I3, I3, which extend out into this cavity through the stem II' and the disc aperture I. Accordingly, the base ID has the character of a sleeve bridging and closing the gap between the discs 4, 4 and the tube ends 3, 3. As shown, the external diameter of the base body I0 corresponds to that of the tube I and its ends are defined by planes radial to the circle represented by the lamp tube I, so that the base completes the lamp circle in appearance as well as structurally.

The base body I0 may be split longitudinally to facilitate putting it on the completed lamp I, If it is made of flexible or resilient material like rubber, a single split at one side of the hollow body may sumce, though as shown it is divided by two splits extending lengthwise of the tube I into separate halves 20, 2|, which are secured together by a screw 22 extending through one half and taking into a threaded hole in the other half, Figs. 4 and 5. As shown, these parts 20, 2| are provided with mating dowel sockets and projections 23, 24, Fig. 3, to facilitate assembling them in proper registry. As rigid material for a base thus constructed, plastics like those known commercially as Bakelite" and Lucite are very suitable, the latter being obtainable in a translucent white which makes it a very good match for the unlighted tube I; indeed, it even "lights up" from the lamp when in operation. If the flt or grip of the base I'Ii around the shoulder(s) of the discs 4, 4 does not sufflce, the base can be secured against turning by means 'of cement. such as the ordinary thermosetting incandescent lamp basing cement. Or, if preferred, the base I II can be anti-turningly keyed to one or both discs 4, 4 as by one or more projections on one of these parts fitting into or against one or more notches or shoulders of the other part, as described hereinafter.

As shown in Figs. 1, 4, and 5, the base I0 is provided with contact terminals to which the leads I3, I3 from each lamp end are connected, these terminals consisting of four pins or posts 25 riveted through the wall 'of the base half 20 lying at the inside of the lamp circle, at the bottom of a socket recess 26 in this part, Figs. 1 and 4. As shown, the socket 28 is of general circuof a floor lamp or a table lamp.

There are important advantages in having the base III engage and grip exclusively around the metal discs 4, 4, either on the shoulders of their peripheries, or on those afforded by their bosses or flanges 6, 6, instead of on the glass tube ends 3, 3 as in the above-cited Harrison patent. The discs 4, 4 are very strong indeed to resist any stresses coming to them from the base II; whereas in themselves the tube ends 3, I are comparatively weak. As regards external stresses such as may arise from impacts against the base I0, the discs 4, 4 distribute such stresses to the whole of their joint with the tube ends 3, 3; and as regards any tendency of the gripping base halves 20, 2| to deform the discs, this can be so limited by.coordinated design of the discs and the base that virtually no deformation of the discs is possible under any gripping stress that can be imposed. Made by die-stamping or other methods, the diameters of the sheet metal discs 4, 4 and of their bosses or flanges 8, 6 can be kept very uniform-far more so than the glass tube ends 3, 3-and thus the possible gripping stresses can be closely controlled. Moreover, the bosses or flanges 6, 6 are not directly united to the glass of the tube ends, so that slight deformation of these parts by the grip of the base II or in resistance to any tendency to turn the base need not involve deforming or stressing the glass, except as torsion stress may be exerted oh the. whole joint'between a disc and the tube end.

Fig. 6 illustrates one way of orienting the base I0 relative to the plane of the tube I and keying it against rotation. For this purpose, one or both discs 4, 4 may have key lugs III, 3|, each formed by cutting two pairs of slits in the flange 9 outward from the opening I and bending up the tongues between each pair of slits. As shown, these lugs 30 are so located that when the disc 4 and its boss 6 are engaged in the internally shouldered end of the base III, the edges of the lugs engageor fit against the diametral surface of the base half 20, inside the smaller bore of the half 2I.

Fig. 7 illustrates another way of orienting and keying the base Iii, the diilference being that the sheet metal of the boss 6 of a disc 4 is notched out at 3i, and the base part 20 is moulded with a projection 32 to engage or flt in this notch 8|.

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

An electric lamp comprising a tubular envelope of non-linear configuration containing electric energy translation means and having its ends disposed in spacedopposed relation, sheet metal discs fused to the said ends of the envelope, at,

ends of said envelope around said discs and providing surfaces at its interior directly engaging said lug means to orient the base member in a predetermined position on said envelope, said base member carrying contact means electrically 5- connected to the said electric energy translation means in said envelope.

ALFRED GREmER. AUGUST W. SEITZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 10 Name Date Harase Dec. 15, 1931 Number Number 6 Name Date Kreflt Dec. 21, 1937 Cartun Apr. 12, 1938 Gustin June 'I, 1938 White Apr. 18, 1939 Greiner Feb. 20, 1940 Aicher Dec. 23, 1941 Lompe Sept. 8,1942 Harrison Jan. 11, 1944 Geiger Jan. 2, 1945 Thomas Jan, 8, 1946

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