Патент USA US2106689код для вставки
Jan. 25, 1938. c. H. BRASELTON 2,106,689 INCANDESCENT ELECTRIC LAMP _ Filed Aug. 25 , 1932 INVENTOR ‘2,106,689 Patented Jan. 25, 1938 UNITED STATES PATENT 1' OFFICE ‘2,106,689 INCANDESCENT ELECTRIC LAMP Chester H. Braselton, New York, N. Y., assignor to Sirian Lamp Company, Newark, N. J., a cor poration of Delaware Application August 25, 1932, Serial No. 630,380 2 Claims. This invention relates to incandescent elec tric lamps and particularly-to a light emitting ?lament therefor. Where a tantalum ?lament is used in an elec 5 tric lamp it has the tendency to absorb gases from the interior of the bulb at comparatively low temperatures. The effect of the absorption of gases on the tantalum raises its resistance, and therefore less current will flow through the wire and the wire will not be raised to as high a temperature as originally intended. Thus the longer a tantalum lamp is burned the more gases are absorbed by the ?lament, and they re 1 sistance gradually increases and the light emis sion from the ?lament becomes lower and lower. The rate of absorption, however, is much lower when the tantalum is maintained at relatively high temperatures, and. it is therefore one of the objects of the present invention to maintain a 20 tantalum ?lament at a high temperature re gardless of its absorption of gases so that the rate of absorption will be relatively low and the light emission will be maintained at a constant high ?gure. 25 Another object of the invention is to increase the mechanical strength of a lamp ?lament at high temperatures. Other objects of the invention will be ap parent as the description thereof proceeds. 30 One embodiment of the invention has been illustrated in the accompanying drawing in which: Fig. l is a side elevational view of anelectric lamp embodying the particular type of ?lament; 35 and Fig. 2 is an enlarged view partly in section of the ?lament used. In Fig. 1 of the drawing an incandescent elec tric lamp is shown having the usual form with 40 an envelope ID of glass or other suitable trans parent material provided with an inturned press H which has fused to it at approximately the center thereof an upstanding glass‘rod l2 which (Cl. 176-40) plurality of wires twisted together, one of the wires being tantalum and the other being a wire having a higher melting point than tantalum. For purposes of illustration I have shown in Fig. 2 a tantalum wire l9 twisted together with a 5 tungsten wire 20 and the twisted ?lament thus _ formed wound in a concentrated coil illustrated by the turns 2| at the right hand side of the ?g ure. . When current is run through the ?lament 10 the temperature of the entire ?lament is main tained slightly higher than the temperature would be if the ?lament were made of tantalum only, and thus the tantalum in the ?lament is prevented from absorbing gases and its resist- 15 ance is maintained at a constant ?gure. If, however, the tantalum does absorb some gases and thereby attains a higher resistance, more current will ?ow through the tungsten wire with the result that its temperature will be raised 20 slightly and the temperature of the tantalum will thereby be increased due to its physical contact with tungsten. The ?lament of the invention, therefore, has the advantages of a tantalum ?la ment with the disadvantages thereof largely 25 , eliminated. While a single wire each of tantalum and tungsten may be found preferable the invention also contemplates the use of a larger number of wires either twisted together or braided,‘ and 30 these wires may be equally divided between tan talum and tungsten or there may be one tung sten wire with several tantalum wires or, vice versa. The tightness of the coiling or braiding may also be varied considerably as a loosely 35 wound coil or braid may be made to accomplish the desired result, it being only necessary to have the tantalum within the high temperature zone of the tungsten to maintain the temperature of the tantalum at a point slightly higher than its 40 normal temperature for the current consumed. Other modi?cations of the invention may be resorted to without departing from the spirit 45 part of the bulb and terminates in a button l3. - thereof and I do not, therefore, desire to limit A pair of support rods M are sealed in the press myself to what has been shown and described 45 extends upwardly to a point adjacent the largest II and have lead-in wires l5v connected to the lower ends thereof. The lighting ?lament I6 is attached to the upper ends of the support rods 50 l4 and extends in a circular curve around the button I3, there being a plurality of support wires l'l sealed in the button l3 and provided with pig-tails I 8 at their ends to support the ?lament in its proper position. 55 The ?lament itself is preferably formed of a except as such limitations occur in the appended claims. What I claim is: 1. An incandescent electric lamp comprising a globe having electric circuit leads, a ?lament of 50 tantalum electrically connected at opposite ends directly with said leads, and means for heating said tantalum ?lament to temperatures in ex cess of its normal lighting temperature com" prising a tungsten ?lament electrically connect- 55 2" 2,106,689 ed at its opposite ends with said leads in com plete electrical parallelism with said tantalum ?lament and in contact therewith throughout its length, the cross-section of the tantalum and tungsten ?laments being substantially equal. 2. An incandescent electric lamp comprising a globe having electric circuit leads, a ?lament of tantalum electrically connected at opposite ends ' directly with said leads, and means for heating said tantalum ?lament to temperatures in excess of its normal lighting temperature comprising a tungsten ?lament electrically connected at its opposite ends with said leads in complete elec trical parallelism with said tantalum ?lament and in contact therewith throughout its length. vCHESTER, H. BRASELTON.