US2272512A - Terminal structure for electric lamps - Google Patents

Description

Feb. 1 1942- c. A. COTMAN ETAL TERMINAL STRUCTURE FOR ELECTRIC LAMPS Filed July 12, 1941 Inverfiors Cart A. Co kman, Daniel K. Wright bW W Their- A't'tor-neg.

Patented Feb. 10, 1942 TERMINAL STRUCTURE FOR ELECTRIC LAMPS Carl A. Cotman, Parma, and Daniel K. Wright, Cleveland Heights, Ohio, assignors to General Electric Company, a corporationof New York Application July 12, 1941, Serial No. 402,121

7 Claims.

Our invention relates to electric incandescent lamps and similar devices comprising a bulb having an electrical energy translation element sealed therein and a. base mounted on said bulb. More particularly, our invention relates to a base or terminal structureespecially suitable for devices such as described and claimed in United States Patents Nos. 2,148,314 and 2,148,315, issued February 21, 1939, to D. K. Wright.

One object, of our invention is to provide a base or terminal arrangement for electrical devices of the above type which is simple in construction and very inexpensive, and which is firmly secured to the lamp envelope by mechanlcal means Another object of our invention is to provide an electrical device having a base or terminal arrangement which extends over the exhaust tip of the lamp envelope so as to form a protective shield or guard therefor serving to protect the exhaust tip from external shocks or blows which ordinarily might result in the accidental breakage oi the exhaust tip with conseuuent destruction of the lamp itself.

Further objects and, advantages of our inven tion will appear from the following description cl 2. species thereof and from the accompanying drawing in which:

l isle side elevation, partly in section, oi electric incandescent lamp provided with a terminal arrangement according to our lnventiorl; Fig. 2 a fragmentary rear elevation or" the base portion of the lamp shown in Fig. i; Fig. 3 is a fragmentary perspective view of? the base portion of the lamp shown in l; is fragmentary "view. on an enlarged scale, of the lamp envelope and base in position for assembly.

Referring to the drawing, the invention is there shown in connection with an electric in candescent projector lamp of the sealed beam type such as described and claimed in the above mentioned patents. The lamp comprises a sealed glass bulb or envelope ill consisting of a preformed pressed glass concave reflector section it of heat-resisting glass, and a cover glass or lens section l2, also of heat-resisting pressed glass, sealed together by fusion. The interior surface I3 of the reflector section I l is of any suitable shape, preferably that of a paraboloid, and is covered with a reflecting metallic coating l4, preferably aluminum, so as to form a reflecting surface. Mounted within the envelope Ill, in definite optical arrangement to the focal point of the reflecting surface thereof, is an electric energy translation element or filament l5, preferably in the form of a linear coil of suitable metallic refractory material, such as tungsten. The filament is supported within the bulb ill by, and electrically connected at its ends to, a pair of relatively heavy rigid leading-in wires l6,-|| which extend through openings IS in the reflector section to closed metal cups or thimbles I 9 having their edges or rims fused to and sunk and embedded in the thickness of the glass surrounding the openings H, the thickness of the glass at such points being increased by the provision thereat of glass bossesv 20 on the exterior surface of the lamp envelope. At their outer ends, the metal cups l9 are provided with tubular outward extensions or projections 2| (Fig. 4) of reduced diameter and closed at their outer ends, into which projections the leading-in wires I8, I! extend and are secured by suitable means, such as by solder 22, so as to provide an electrical connection between the leading-in wires endthe metal cups as Well as a farm support for the said wires and the filament The metal cups or thimbles it provide an effective hermetic seal between the leading-in wires and the lamp envelope similar to that de scribed and claimed in United States Fatent No. 2,@98,08u-l3. Wright, issued November 2, 1937. The cups or thiinbles it? are made of a metal to which the glass or the lamp envelope will wet or adhere, and should preferably have an expansion as near possible to that of glass. For heat-resistant glass of the type known as Pyrex, the cups are preferably made either of iron-nicltei-cobalt alloy known as Fernlco, or an iron-nickel alloy containing a proximately l2 per cent nickel.

The lamp envelope it is eidiausted and with a suitable gas through an exhaust tube attached to the reflector section it at its vertex, i. e., at a point between openings 38 so that the exhaust tube is therefore disposed between the metal thimbles ill. After the gas filling is in troclucedinto the lamp envelope, the exhaust tube 23 is tipped oil to provide a flattened exhaust tube 24, as shown in the drawing. The flattened exhaust tube tip it is disposed vin a plane substantially coinciding with the plane passing through the axes of the metal thimbles I 9.

Mounted on each of the metal cups or thimbles i9 and firmly secured thereto, is a metal contact lug or terminal member 25 which together form the base or terminal structure of the lamp. The terminal lugs or members 25 each consist of a strip of metal having lamp attachment portions 26 extending transversely across the rear of the lamp envelope and the outer ends of the metal thimbles l9, 1. e., at right angles to the axis of the reflector section ii, and rigidly secured to the metal cups or thimbles [8. For this latter purpose, the said portions 26 are provided with inturned eyelets 21 which fit over the tubular extensions or teats 2| on the metal thimbles l8 and are firmly secured thereto in a suitable manner, such as by soldering.

The terminal lugs 25 are mounted on the metal thimbles I! with the attachment portions 26 thereof extending towards and in alignment with each other, as shown in Fig. 2, so as to overlie the lamp exhaust tube tip 24 which is disposed between the metal thimbles I9. In this manner, the terminal lugs 25 form a protective shield or guard for the exhaust tube tip 24 serving to prevent the latter from being subjected to impacts or shocks which might cause its breakage. The inner facing ends 28 of the terminal lugs are, however, spaced a slight distance apart so as to prevent the contacting thereof and resultant short-circuiting of the lamp terminals.

To prevent interference between the flattened exhaust tube tip 24 and the overlying portions of the terminal lugs 25, the inner facing ends of the latter are provided with opposed notches 29 which together form a suitable recess for the accommodation therein of the flattened exhaust tube tip 24 should the latter extend far enough out from the lamp envelope to normally interfere with the terminal lugs. The notches 29, in effect, result in the formation of protective ears '0 on the contact lugs 25 which ears form the protective shield for the exhaust tip 24.

At their outer ends, the metal strips 25 constituting the terminal lugs are preferably bent towards the lamp envelope at a suitable angle less than 90', such as say 45 or thereabouts, to form angular portions 3| in which suitable binding screws 52 are threaded for the purpose of fastening the current supply wires 55 from a source of power. The current supply wires 33 may be fastened to the terminal members 25 by means of conventional connector lugs 34.

The outermost end portions of the terminal lugs 25, beyond the angular portions 3! thereof, are further bent towards the lamp envelope in a direction substantially at right angles to the transversely extending attachment portions 26, i. e., in a direction longitudinally of the lamp reflector axis, so as to form bracing leg portions 25. The free edges 56 of the said bracing leg portions 35 rest on the convex rear surface 31 of the lamp envelope so as to brace the terminal lugs 25 and thereby provide a firm mounting of the same on the lamp. I'he edges 36 of the bracing legs 55 are preferably made of a concave shape of greater curvature than that of the convex rear surface 51 of the lamp envelope, in order that each edge may engage the said surface 21 at two spaced points, that is, at the opposite ends of each edge 36, thus providing a better and firmer support for the terminal lugs.

The terminal lugs 25 are preferably punch d, from a strip of metal of the desired width and thickness. To effect a material saving in the metal stock out of which the terminal lugs are formed, the extreme end portion of the bracing legs 35 are preferably made of reduced width and of the same configuration as the notches 29, as shown at 25 in Fig. 3, so that they may be formed out of the metal which is punched from the next succeeding terminal member to form the exhaust tip receiving notch 29 of such succeeding terminal member.

To prevent vibration of the connector lugs 24 which fasten the current supply wires 32 to the terminal members 25, which vibration is otherwise apt to gradually loosen the binding screws 32, the terminal lugs 25 may be provided with suitable locking tongues or tabs 2! punched therefrom at points adjacent the binding screws 32. The locking tabs 39 extend out from the outer surface of the terminal members with their raised free ends 40 disposed closely adjacent the peripheries of the heads of the binding screws 32. In operation, the locking tabs 28 are engaged by the connector lugs 34 of the current supply wires and so lock the same against any vibration thereof which might cause the gradual loosening of the binding screws.

The improved terminal construction according to the invention is very simple in construction and inexpensive to manufacture, and besides providing adequate protection for the exhaust tip against accidental breakage, also provides a base structure of minimum height, i. e., a base which extends a minimum distance out from the surface of the lamp envelope. Such feature thus enables the use of a lamp housing of minimum depth.

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

1. An electrical device comprising a sealed bulb having a plurality of metal thimbles mounted exteriorly of said bulb, and a terminal structure for said device comprising a plurality of metal strips secured one to each of said metal thimbles, each of said metal strips having an end thereof abutting against the surface of said bulb.

2. An electrical device comprising a sealed bulb having a pair of spaced metal thimbles mounted exteriorly of said bulb and an outwardly extending exhaust tube tip disposed substantially between the said metal thimbles, and a terminal structure for said device comprising a pair of metal strips secured one to each of said metal thimbles and extending towards each other so as to substantially overlie said exhaust tube tip and thereby form a protective shield therefor.

3. An electrical device comprising a sealed bulb having a pair of spaced metal thimbles mounted exteriorly of said bulb and an outwardly extending exhaust tube tip disposed substantially between the said metal thimbles, and a terminal structure for said device comprising a pair of metal strips secured one to each of said metal thimbles and extending towards each other so as to substantially overlie said exhaust tube tip and thereby form a protective shield therefor, the facing edges of said metal strips being slightly spaced from each other and having opposed notches forming an enlarged recess for the accommodation of the said exhaust tube tip therein.

4. An electrical device comprising a sealed bulb having a pair of spaced metal thimbles mounted exteriorly of said bulb, the outer ends of said metal thimbles having a cylindrical extension. and a terminal structure for said device comprising a pair of metal strips secured one to each of said metal thimbles, each of said metal strips having an eyelet fitting over the said cylindrical extension on the associated metal thimble and being secured thereto.

5. An electrical device comprising a sealed glass bulb having a convex outer wall portion, a

plurality of spaced metal thimbles mounted exteriorly of said bulb, said metal thimbles having their edges embedded in and fused to the glass constituting said bulb, and a terminal structure for said device comprising a plurality of metal strips secured one to each of said metal thimbles at the outer ends thereof, each of said metal strips having an end abutting against the said convex surface of said bulb, said end being formed of a concave shape of greater curvature than that of said convex bulb surface so as to engage the said convex bulb surface at two spaced points.

6. An electrical device comprising a sealed bulb having a convex outer wall portion, a pair of spaced metal thimbles mounted exteriorly of said bulb, and a terminal structure for said device comprising a pair of metal strips secured one to each of said metal thimbles, each of said metal strips comprising an attachment portion extending transversely across the outer end of the associated thimble and secured thereto, an angular portion bent towards the bulb and provided with means for attaching a circuit connection wire to said angular portion, and a bracing leg portion extending substantially at right angles to the said attachment portion and having its free end abutting against the convex outer wall portion of said bulb tothereby provide an additional support for said metal strip.

'7. An electrical device comprising a sealed bulb having a convex outer wall portion, a pair of spaced metal thimbles mounted exteriorly of said bulb, and a terminal structure for said device comprising a pair of metal strips secured one to each of said metal thimbles, said metal strips extending transversely across and being secured to the outer ends of said thimbles, one end of each of said metal strips being bent towards the said bulb at an angle less than ninety degrees to form an angular portion, said angular portion being provided with means for attaching a circuit connection wire to said angular portion, and said end beyond said angular portion being further bent into a position substantially at right angles to said transversely extending portions to thereby formbracing leg portions, the free end of said bracing leg portions abutting against the said convex outer wall portion of said bulb to thereby provide an additional support for said metal strip.

CARL A. COTMAN. DANIEL K. WRIGHT.

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