US1565564A - Method of and means for introducing potassium or other vapors in lamps - Google Patents

Description

Dec. 15, 1925- 1.565.564

A. M. HAGEMAN 1 METHOD OF AND NBANS FOR INTRODUCING POTASSIUM OR OTHER VAPORS IN LAMPS Filed July 23, 1923 INVENTOR AARON M. HAGENAN ATTORNEY Patented Dec. 15, 1925;

UNITED STATES PATT oFFicE.

AARON MARTIN HAGEMAN, OF BLOOMFIELD, NEW JERSEY, ASSIGNOR TO WESTING HOUSE LAMP COMPANY, A CORPORATION OF PENNSYLVANIA.

METHOD OF AND MEANS FOR INTRODUCING POTASSIUM OR OTHER VAPORS IN LAMPS.

Application filed July 23, 1923. Serial- No. 653,116.

To all whom it may concern:

Be it known that I, AARON MARTIN HAGE- MAN, a citizen of the United States, and a resident of Bloomfield, in the county of Essex and State of New Jersey, have invented a new and useful Improvement in Methods of and Means for Introducing Potassium or Other Vapors in Lamps, of which the following is a specification.

This invention pertains to electric lamps of the gas-filled type and has more particular reference to a method of and a means for the introduction of a free alkali metal into neon lamps.

It is an object of the invention to provide a practical and efficient method of introducing an alkali metal such as potassium into an electric discharge device or other evacuated or gas-filled container to act as a getter and to reduce the electrode voltage drop.

It is another object to devise a means by which an alkali metal such as potassium may be easily and readily introduced within an evacuated or gas-filled container.

Other objects will become apparent from the description and claims and from the drawing in which the figure is an elevation of a discharge lamp of the gas-filled type embodying the'invention.

It is well known that the starting and op,- erating voltages of neon or other gas-filled glow lamps may be much reduced by the introduction of an alkali metal therein. The best results have been obtainedby the 85 use of potassium in vapor form, which seems to increase the ionization between or the electron discharge of the metal electrodes as well as to reduce the resistance of the gap between \hem. This is, however, but a 40 theory of the principal cause of the peculiar phenomenon that takes place upon the intro duction of a vapor of an alkali metal into this type of discharge lamp.

Considerable difiiculty has been encoun- 45 tered in using metals of the class. of potassium since their low melting points and susceptibility to oxidation or combination with other metals or compounds destroys their usefulness as voltage drop reducers and clean-up agents and renders their manipulation by the usual methods and means extremely dangerous. Potassium for instance with a melting point of 62 C. will readily take fire from contact with the human skin making it necessary to use costly apparatus and methods to properly handle it.

I find that an amalgam of mercury and potassium may be so prepared in the solid state that a condition of reduced activity is reached in which condition, the amalgam may be cast into pellets of a desired size and shape and introduced into the lamp or other device before the potassium can react with the moisture and gases in the surrounding atmosphere. Such an amalgam may be prepared by heating pure mercury to from 65 to 70 C., which is above the melting point of potassium (62 C'.) and, by

means of a pair of tweezers, immersing small pieces of clean and pure potassium beneath the surface of the heatedmercury. The potassium will melt and rapidly form a liquid potassium-mercury amalgam with the 0- tassium thoroughly and homogeneously incorporated with the mercury. Stirring may help to completely diffuse the two metals. By this method it was found possible to obtain an amalgam having a softening point as high as 110 C.

Amalgams containing varying percentages of potassium may be readily prepared by this method but I may prefer to use an amalgam containing 2% of potassium for neon glow lamps. Difficulty may be experienced in preserving the amalgam in pellet form in the open atmosphere although it may be readily introduced within a lamp and maintained in a solid condition during the process of manufacturing the lamp if reasonably protected from heat during the sealing-in and exhaust operations.

In introduciing the amalgam into the lamp I prefer to secure it to a portion of the interior structure in some suitable manner. For instance as is illustrated in the drawing, I may secure a cup 2 of suitable material to the terminal of one of the non contacting electrodes 4;, 6, which are secured in the usual manner to lead-in wires 8 and within the usual bulb 10. The cup may be made of copper or any material not readily attached by the potassium, suitable for the purpose and is attached to the end of the electrode in any desired manner; The cup may be packed or filled with the prepared amalgam and may be positioned in any manner desired with respect to the sealing-in and exhausting operations as the mercury of the potassium amalgam readily amalgamates with copper and adheres to the cup, if the cup be made of such metal as copper, with suflicient tenacity to prevent it from being jarred out. Any heat reflected from the sealing-in or tipping operations toward the cup is conducted over the wire electrodes, which act as a heat shield, and thereby dissipate the heat.

After the lamp or other vessel is ex-' hausted, neon or other gas or gases, suitablefor the purpose, may be introduced in i any manner known in' the art. The alkali metal is volatilized by application of heat from the exterior or by' connecting the electrodes across a source of ower of sut ficient potential to cause s cient heating of the electrodes to volatilize it. Other methods of volatilizing the alkali metal such as by high frequency inductive heating of the amalgam by eddy currents induced therein, may be resorted to as will be readily apparent. It may be preferable to cold exhaust the lamp' and if this be done, it may be necessary to treat 'out'any occluded gases from the electrodes prior to their assembly in the lamp structure.

While this invention has been described particularly with reference to the introduction of potassium-into neonlamps, it is to be understood that it is not so limited but broadly comprehends the manipulation of the alkali metals in such manner that they may be readily introducedinto evacuated or gas-filled containers of various types and readily handle for anydesired purose. I do not limit myself therefore to the particular form or structure shown as many modifications of the invention will present themselves without departin from its spirit or from the scope of t e appended claims.

What is claimed is:

1. The method of introducing a free alkali metal into an electrical discharge device which comprises preparing a relatively high melting point amalgam of said metal, and

introducing-the amalgam in the said device in contact with a metal part of the device. (1

.2. The method of introducing the vaporof an alkali metal into, an electrical discharge device comprising introducing .a

relatively high melting point amalgam of said metal into said device in contact with a metal part thereof and vaporizing said alkalimetal.

3; The methodof introducing the vapor of an alkali metal into an electrical is-' charge deviie comprising introducing an amalgam of said metal having a relatively high melting point into said device in conwhich consists in mixing said metal with 'mercury and applying the mixture as an amalgam to a metal part of the device. 6. The method of introducing an alakli metal into a discharge device consisting in applying said metal in the form of a mercury amalgam to a copper body and introducing the copper body into the device. 7. The method of introducing potassium into a discharge device having metal electrodes. .consisting in attaching a copper body to one of said electrodes and applying potassium in the form of an amalgam to the copper body.

8'; The method which comprises positioning an amalgam of anunstable metal on a metal portion of the device-in proximity to the path of discharge and causing a discharge whereby said unstable metal is volatilized.

V of reducing the starting a voltage of gas-filled discharge devices prising, supporting an amalgam of an un-' stable metal within said device, from a metal part thereof in the vicinity of the path of discharge and causing a discharge whereby said unstable metal is volatilized.

10. A commercially unfinished gas filled electricdischarge device having solid electrodes and means including an alkali metal in a relatively stable state attached to one of said electrodes by mercury and cooperative therewith whereby said alkali metal is rendered unstable upon the passage of a current between said electrodes.

11. The) method of introducing an alkali metal into a discharge device which consists in forming an alloy of the metal which. will adhere to metal at normal temperatures and applying said alloy to a metal part of said evice prior to the sealing of sald part into the device. V

12. The method of introducing an alkali metal into, an evacuated container which consists in' forming an amalgam of the Ill metal, applying the amalgam to another metal with which the mercury of the amalgam readily amalgamates and introducing said last mentioned metal into thedevice.

13. The method of introducing an alkali metal into an electrical discharge device consisting in applying said metal in the AARON MARTIN HAGEMAN.

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