US1154514A - Incandescent lamp. - Google Patents

Description

R. JACOBY.

INCANDESCENT LAMP.

APPLICATION FILED IuIIEz. I9I4.

l 9 1 54,5 l 4@ Pa'ented Sept. 2l, 1915 UNTTED sTATEs PATENT onirica.

RICHARD JACOBY, 0F BERLIN, GERMANY, ASSIGNOR TO GENERAL ELECTRIC COMPANY.

" A CORPORATION OF NEW YORK.

INCANDESCENT LAMP.

Specification of Letters Patent.

Patented Sept. 21, 1915.

Application led .Tune 27, 1914. Serial No. 847,715.

T0 all 'whom it may concern Be it known that I, RICHARD JACOBY, a subject of the King of Prussia, residing at Berlin, Germany, have invented certain new and useful Improvements in Incandescent Lamps, of which the following is a specification.

The present invention relates to incandescent lamps and particularly to lamps in which a metal filament is\operated in an envelop containing a gas.

It is the function of the gas to reduce the vaporization of the filament and thus to enable it to be operated at a higher temperature. The low heat conductivity of the heavier 'rare gases of the atmosphere, for example, argon renders their use in gasfilled lamps advantageous. It has been found, however, that in lamps filled with rare gases the film of material deposited on the bulb is more opaque than in nitrogenfilled lamps. Lamps filled with these rare gases also are subject to arcing at a lower temperature than lamps filled with nitrogen. In accordance with the present invention these drawbacks are overcome without substantial sacrifice of the low heat losses of the rare gases by adding a small amount of nitrogen.

The accompanying drawing shows somewhat diagrammatically, an incandescent lamp illustrating one form commonly employed when a gas filler is provided.

This lamp comprises an elongated envelop 1, in which is mounted a coiled filament 2 vwhich commonly consists of tungsten, although other refractory metals also may be used. The diameter of the glower should be so chosen that it may be operated at excessively high tempera-tures for a good commercial life of the lamp. The increased diameter decreases the proportionate convection and conduction losses so that the filament may emit light at an efficiency higher than it would have in a'vacuum if operated so as to have the same useful life. Coilin the filamentin a close spiral gives the e ect of `an increased diameter. The filament is attached either by welding or mechanically to supporting wires 3 and 4, which project into the globe to locate the filament neark the lower end. Electrical energy is supplied by'leading-in conductors 5 and 6 sealed into a stem 7'. in the usual Well understood manner.

The lamp is filled with a mixture of a rare gas or gases and nitrogen having a pressure measured when the lamp is cold, of about 400 mm. of mercury or as low as about 100 mm., but while the higher range of pressures is preferable the pressure should not be so high'as to endanger the bulb when the filament is heated. It is the functionof this gaseous atmosphere to: reduce the tendency of the filament to vaporize and also to carry away by convection currents l the small amount of vapor which is inevitably pro` duced. The gas can suppress but not entirely prevent vaporization of the filament.

Although the lamp is so constructed that the vaporized material is deposited near the upper end of the globe where it will not obstruct the light, in time some of the material may be deposited near enough to the filament to cut olf the light. When using the rare gases of the atmosphere, for example, argon, and krypton which are extremely in ert chemically and for this reason are known also as the noble gases, the film of vaporized metal is black and opaque as the deposited metal remains chemically uncombined. 1

Experiments have shown that when only a very small amount of nitrogen is added to the argon or other rare gas filling that the deposit on the walls of the globe assumes a lighter color and obscures less light. This light colored deposit has been found in the tungsten lamp to be a nitride of tungsten. This action takes place even when the amount of nitrogen is very small, for example, one-tenth of one per cent. A small amount of nitrogen does not materially reduce the heat conductivity, as this is proportional to the relative amounts of argon and nitrogen present. Of course, in some cases greater amounts of nitrogen may be used, say up to 10% or even more, the heat con` ductivity being correspondingly higher. The presence of nitrogen also has been found to reduce the arcing to a surprising extent, the discharge voltage increasing rapidly with even a small nitrogen content instead of being proportional to the nitrogen content as might be expected. Evena small percentage of nitrogen raises the dischargevoltage to the value characteristic of pure nitrogen.

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

1. The combination of an envelop, a gloWer of refractory metal mounted therein, means for supplying energy thereto, and a mixture of argon and' nitrogen surrounding saidv lower. Y

2. he combination of an envelop, a tungsten filament mounted therein, means for supplying energy thereto, ami gaseous mixture consisting largely of argon and a small amount of nitrogen surrounding said Ela-ment.

3. An incandescent lamp, comprising a globe, a tungsten lament located therein, currentconductors for said filament, and a gas filling at relatively consideralile pres sure for said globe, comprising nitrogenand argon.

4. An incandescent lamp comprising a."

transparent envelop, a gaseous lling .comprising argon and about 0.1% to 10% of nitrogen in said envelop, and a tungsten glower therein proportioned in size to operate at an efficiency higher than the efficiency saidL gloWer would have in a vacuum if operated so as to have the same useful life.

In Witness whereof, I have hereunto set my hand this 11th day of J une, 1914.

RICHARD J ACOBY.

Viitnesses D. KARL NEY, ERNST FRIEDERIGH.

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