US1581690A - Two-filament street-series lamp - Google Patents

Description

April 20 1926! r 1,581,690

A. L. POWELL TWO-EILAMENT STREET SERIES LAMP Filed Dec. 19 1 1 INVENTOR ARTHUR L- powzu.

ATTOYRNEY the leading-in wire 4,- filament 9 and the leading-in wire thus, the filament 9 is normally maintained in circuit. The filament 9 may, however, burn out or be ruptured in some manner, thereby preventing the passage of current. It is then desirable to engage another filament in order to'maintain the continuous luminosity of the lamp as well as to prevent the series; circuit'from becoming disrupted. a

The present embodiment of the invention provides a secondary filament l0, preferably of the same current rating as the primary filament and having its ends connected to the leading-in wire 5 and to an auxiliary or supplemental conductor 11. This conductor is provided with a projection 12 and is adapted to be positioned with the said projection adjacent, and preferably parallel, to the end 8 of the leading-in wire 4. It has been found desirable to-support the supplemental conductor 11 by a glass head 13 with sufficient material intermediate the leadingin wire and the conductor to afford adequate insulation. The supplemental conductor 1]. is juxtaposed with respect to the leading-in wire 4 so as to provide a relatively small gap 14-between the projection 12 and the end 8' of the leading-in wire.

The leading-in wires are usually made of nickel and are consequently, readily fusible. Thus, if the primary filament breaks and the circuit is thus disrupted, an arc will be first produced between the broken ends of the filament and, as the filament wire melts, the are will continue between the leading-in wire 5 and the end 8 of the leading-in wire 4, whereupon the ends of the. leading-in wires will become molten and-the end 8 of the leading-in wire 4 will quickly drop and make contact with the end 12 of the sup-.

plemental conductor 11, or. an enlargement or bead will form on the leading-in wire and span the gap 14, thereby joining the.

leading-in wire 4 to the conductor. The resistance being less in the ,circuit formed throughthe connection between the leadingin wire 4 and the supplemental conductor 11 than in the arc gap, the current will then pass through the leading-in wire 4, the conductor 11, the filament 10 and thence through the leading-inwire 5, and cause the filament 10 to become incandescent.

It is obvious that, if desirable, the filament 10 might be. dispensed with, in which case, the conductor 11 would be connected to the leading-in wire 5. lVith this construction, substantially the same advantage would be obtained as abowe described, inasmuch as provision is made for a continuation of the passage of current upon the failure of the filament 9; the are being again employed to perform the function of closing the circuit as is the case in the employment of the two filaments.

The end 8' of the leading-in wire 4 and the end 12 of the conductor 11 are so posi tioned with respect to each other as to provide a gap-14 of such dimension that, if the filament breaks when cold, the line voltage "0 will jump the gap and cause a fusing of the end 8 to the supplemental conductor 11, thus putting in circuit the secondary filament or in the event that the secondary filament is omitted, a connection will be made and the continuity of the circuit will be maintained.

A lamp provided with the present invention may be burned in practically any position. For instance, if the lamp is placed in service with the tip down,;a break in the filament will first cause an arc tobe produced between the ends thereof and then between .the leading-in wire wire 5 and the end '8 of the leading-in wire 4. This are will cause the end of the leading-in wires to fuse and pro: (luc an accumulation of metal, in other words, form a bead or ball at the ends of the leading-in wires. The accumulation of metal thus formed at the end 8 will efiec't a bridging of the gap 14 to out in the filament 10 or close the circuit ,in the event that the filament 10 is omitted.

It is evident that the present invention may be applied in an expeditious and economic manner to the type of lamp illustrated withoutany alteration in the standard 0011- e struction. Any commercial lamp of this type may be equipped with the present invention during manufacture, at which time the supplemental conductor may besecured to the leading-in wire or to any other suitable portion of the structure, and the filament may be connected between the said conductor and the opposite leading-in.wire.

I have shown and described one form of a device which has been found a desirable. embodiment of the invention, it is, however, to be understood that the invention is not restricted to the structural. details shown and that many modifications may be made therein without departing from the spirit and scope of the invention as set forth in the appended claims.

What is claimed is:

1. An electric lamp comprising a filament, leading-in wires connected to opposite ends of said filament, a supplemental'conductor supported by and insulated from one of said leading-in wires, conducting means between said'supplemental conductor and the other one of said lg ding-in'wires, one end of said conductor be: g positioned in near relation to an end of the supporting leading-in wire, whereby an are produced by a break in said filament fuses said leading-in wire and said conductor to provide a closed circuit.

2. An electric lamp comprising leading-in wires of relatively large diameter and low fusing point, a primary filament having its ends connected tothe exposed ends of saidported upon and insulated from one of said leading-in wires, one'end of said conductor being spaced from the end of the leading-in wire upon which it is supported, theopposite end of said supplemental conductor being connected to the other leading-in wire by an auxiliaryfila1nent, whereby an are created b failure of the primary filament effects a fusion of the adjacent ends of the leading-in wire and the auxiliary conductor supported thereon, causing said auxiliary filament to be put in circuit.

An electric lamp comprising a primary and a secondary filament, conductors of relatively low fusing point being connected to said filaments, said secondary filament being normally maintained out of circuit by a gap between the conductor connected thereto and the conductor connected to the primary filament, whereby the are created when said primary filament fails, operates to fuse said material and close said gap to connect said secondary filament in circuit,

4. An electric lamp comprising a stem having a. press, leading-in wires secured in said press, a filament connecting the ends of said leading-in wires, a supplemental con ductor supported by and insulated from one of said leading-in wires, one end of said conductor-being positioned, adjacent to one of said leading-in wires to provide a gap therebetween, and a filament connecting said conductor and the other leading-in wire, said gap being of such width that an arc will pass thereover upon the failure of said 1nemtioned filament and cause said supplemental conductor and adjacent leading-in wire to be welded together.

5. An electric lamp comprising leading-in wires, a primary-filament connected to the ends of said leading-in wires and normally in circuit, at least one of said wires being of a metal of relatively low fusing point, a supplemental conductor supported by and insulated from said low fusing point leading-in wire, a secondary filament connected to the other leading-in wire and to said supplemental conductor, the relative positions of a portion of the leading-in wire supporting the supplemental conductor and a portion of said conductor being such, that upon a failure of the primary filament, said conductor and leading-in wire will become

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