US2134574A - Electric incandescent lamp - Google Patents

Description

Oct. 25, 1938. E. B. PINKL:E

ELECTRIC I NCANDESCENT LAMP Filed Aug. 24, 1937 Figl.

lrwverwtor: Emma B Pinkie,

' He Aotorney.

Patented Oct. 25, 1938 PATENT OFFICE ELECTRIC INCANDESCENT LAMP Emma B. Pinkie, East Cleveland, Ohio, assignor to General Electric Company, a corporation of New York Application August 24,

' 3' Claims.

My invention relates to electric incandescent lamps and more particularly to'high wattage lamps. Still more particularly, my invention relates to an improved joint between the lamp filament and its leading-in conductors.

Heretofore, in high wattage lamps of the type wherein the filament comprises a number of coiled segments arranged substantially parallel to each other, it has been the practice to wind the filament with extra coiled segments at the ends thereof which were short-circuited by inserting a mandrel therein and then welded to-- \gether with their mandrels to the leading-in conductors. Such a joint has the disadvantage that the mandrel may not make a positive contact with some of the turns of the end segment so that those turns are heated by the current passing through the lamp thereby increasing the efiective length of the filament over its designed length. Moreover, the welding operation tends to make the tungsten filament brittle so that it is liable to break off if the lamp is jarred.

One of the objects ofmy invention is to provide an improved form of joint between the filament and the leading-in conductors. Another object is to provide a joint in which the end segments of the filament are effectively short-circuited. Still another object is to greatly increase the strength of the joint and to provide a good mechanical and electrical connection of the filament to the leading-in conductors.

Further objects and advantages of my invention will appear fromthe following description of a species thereof and from the drawing in which Fig. 1 is an elevation of one form of incandescent lamp embodying my invention; Fig. 2 is an elevation, partly in section and on an enlarged scale, of a portion of the filament joint; and Fig. 3 is a section along the line 3-3 of Fig. 1 showing a portion of the filament and its supporting structure.

Referring to the drawing, the lamp shown therein comprises a glass bulb l0 having a base construction of the type shown and claimed in United States Patents Nos. 1,967,852 and 2,069,- 638, D. K. Wright, and consisting of a pressed glass cup portion ll having tubular bosses l2-l2 thereon to which are sealed metal thimbles l3-|3 which serve for mounting the lamp and for conducting current thereto. Channel-shaped metal supports or leading-in conductors l4l4 are secured at their ends within the thimbles |3-l3 and extend into the bulb Ill. The leads l4-I4 may be made of nickel-plated steel and may be provided with rod or wire, end portions 1937, Serial No. 160,621 (Cl. 176-38) l5-l 5, of molybdenum for example, welded thereto and extending on opposite sides of the tungsten filament It. The leads are held in rigid spaced relationship by cross-bars ||-l8 of insulating material, preferably a ceramic material such as siliminite. The cross-bar I1 is secured to the leads M-M by short lengths of wire l9l9 threaded through holes in the ends of the crossbar and in the leads and welded to the leads. The cross-bar I8. is secured to the ends of the 10 lead extensions I5-I5 by similar wires 20-40 welded to said extensions.

The filament l6 illustrated in the drawing is' of the biplane type comprising a plurality of parallel coiled segments. joined by upper and 15 lower uncoiled or bight portions 2| and 22 respectively, the alternate segments in this case being located in separate planes so that one-half of said segments are in one plane and the other half of said segments are disposed behind said 20 first half in another plane. "The filament is supported at the top by support wires 23 having hooked lower ends engaging the upper bights 2| and secured at their upper ends to the cross-bar H. The lower bights 22 are rigidly secured, pref- 25 erably by welding, to the upper ends of anchor wires 24, the lower ends of which are rigidly secured to an insulating bridge member 25 which may be made of zircon. The said anchors may be embedded in the bridge25. Each of' gulde 30 wires 2626 has one end secured to the bridge 25 and the other end loosely coiled around a lead extension l5 so as to be freely slidable thereon so that the filament I6 is free to expand in a longitudinal direction and the bridge 25 moves therewith but is prevented from rotatingby the said guide wires 26 thereby preventing the segments of the filament from twisting. The bridge 25 is further guided by a wire 21 secured thereto and extending through a hole in the cross-bar l8.

Each end of the filament I6 is wound with a coiled segment 28 (Fig. 2) over which is screwed a coil 29, preferably of tungsten wire, of substan tially the same length as the said segment 28 to short-circuit the said segment. The coil 29 is 45 of the same pitch as the segment 28 and preferably is made of a wire of slightly smaller diameter. A conductive support or mandrel 30 extends through the segment 28 which is securely held between a hooked end 3| of the mandrel 50 and the cross-bar H, the said mandrel extending through a holein'said cross-bar and being secured, preferably by welding, to the lead It. The hook 3| on the end of mandrel 30 may be omitted if desired sincethe segment 28 grips the mandrel quite tightly. Such a joint adds greatly to the having a coiled end portion, a coil screwed over strength of the lamp, provides a good mechanical said coiled end portion of said filament and shortand electrical connection of the filament to the circuiting the turns thereof, and a conductive leads and assures the short-circuiting of all 01' mandrel in contact with and extending through the turns in the filament end segments 28. said coiled end portion or said filament and 5 What I claim as new and desire to secure by r h Said r sr $0 One d l s. aid Letters Patent of the United state is; filament end portion and the coil thereon being 1. In an incandescent lamp, the combination secure y d e w e sa d c ssa and the end of a conductive lead, a filament having a coiled of sa d mand e end portion, a coil screwed over said coiled end In n incandescent p. the com ination 10 portion of said filament and short-clrcuiting the f a filament, aconductive support f r S pp y n turns thereof, and a conductive mandrel in concurrent to said filament, said filament having a tact with and extending through said coiled end coiled end portion surrounding and making elecportion of said filament and secured to said contrical contact with said support and a coil screwed ductive lead at a point removed fromsaid coils. over said coiled end portion of said filament and 15 2. In an incandescent lamp, the combination short-circuiting the turns thereoi. 01 a pair of spaced conductive leads, an insulating cross-bar extending between said leads, a filament EMMA B. PINKLE.

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