US2030399A - Gaseous electric discharge lamp device - Google Patents

Description

Feb. 11, 1936. R, RO P; 2,030,399

GASEOUS ELECTRIC DISCHARGE LAMP DEVICE 'F'iled A 20, 1935 1 INVENfOR WW ATTORN'EY Patented Feb. 11, 1936 2,030,399 PATENT OFFICE GASEOUS ELECTRIC DISCHARGE time navrca Robert Rompe, Berlin, Germany, assignor to General Electric Company, a corporation of New York Application August 20, 1935, Serial No. 37,054 In Germany August 27, 1934 1 Claim. (01. 176-122) The present invention relates to gaseous electric discharge lamp devices generally and more particularly the invention relates to such devices haigng .a fluorescent material associated therewit The object of the present invention is to provide a method of operation for a gaseous electric discharge lamp of this type whereby substantially no visible light is emitted ,by the gaseous electric discharge and the fluorescent light emitted by the lamp is of higher intensity than that emitted by prior lamps; Another object of the invention is to provide a method of operation for a gaseous electric discharge lamp whereby the greater part of the energy consumed by said lamp is transformed thereby into ultra-violet light. Still further objects and advantages attaching to the device and to its use and operation will be apparent to those skilled in the art from the following particular description.

In accordance with these objects the method of the present invention consists in operating the lamp on a high frequency current of more than 10 cycles, a current density of less than 10 milliamperes per cm tube section and with a mercury vapor pressure of 10- mm. vThe low current density, the extremely low vapor pressure and the very high frequency of the current cooperate to the end that the discharge in the lamp emits little or no visible light and the greater part of the electrical energy supplied to the lamp, transformed into visible light in prior lamps, is converted into ultra-violet light. Since the ultra-violet light is transformed into visible light by the fluorescent material associated with the lamp practically without losses a maximum intensity of light from the fluorescent material is obtained from a lamp operated in accordance with the method of the present invention.

In the drawing accompanying and forming part of this specification a gaseous electric discharge lamp which can be operated in accordance with the method of the present invention is shown in a side-elevational, partly sectional view.

Referring to the drawing the lamp comprises an elongated, tubular container I having electrodes 2 and 3 sealed into the endsthereof and a gaseous atmosphere therein comprising a starting gas, such as argon, and a quantity 5 of vaporizable material, such as mercury. Said electrodes 2 and 3 are carbon electrodes, When desired, thermionic electrodes, or cold, sheet metal electrodes or external electrodes are used.

Said containerl has a coating 4 of fluorescent material, such as zinc sulphide, calcium tungstate, magnesium molybdate, zinc silicate, or zinccadmium sulphide, on the inner surface thereof. The coating 4 is applied to the inner surface of said container I by methods now known inthe art, such as by heating the container I to the softening temperature and propelling particlesof the fluorescent material toward the softened inner surface of said container I so that the particles are partially embedded in said sur- 0 face, as disclosed in copending application, Serial Number 758,514, filed December 20, 1934 or by partially embedding the fluorescent material in a layer of light transmitting enamel applied to the inner surface of said container I and having a lower softening temperature than said container I, as disclosed in co-pending application Serial Number 758,028, filed December 18, 1934. p

When the lamp is operated by the above described method the high frequency discharge emits substantially no visible light and the fluorescent coating 4 emits fluorescent light of high intensity. 7

The low vapor pressure in the lamp is obtained by maintaining the temperature of the container I, or a part of said container I, as by cooling to that temperature corresponding to the desired vapor pressure, or .by limiting the quantity of mercury in the lamp to an amount such that the desired vapor pressure exists in the lamp at 2 the operating temperature of the container I. It will be understood, of course, that numerous changes in the form' and details of the device and in its use and operation may be made by those skilled in the art without departure from the spirit and scope of the invention, for example, the coating 4 is applied to the outer surface of said container I, when desired, or the fluorescent material is applied to a light transmitting screen mounted separate from but in ultra-violet light receiving relation to the lamp, when desired, or

1 the fluorescent material is totally embedded in the wall of the container I, when desired. In.

these modifications of the invention the container I must be made of an ultra-violet transmitting material, such as quartz.

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

The method of operatingfa gaseous electric discharge device comprising a sealed container, a

gaseous atmosphere therein comprising a vapor capable of emitting ultra-violet light when excited by an electric discharge, electrodes in operative relation thereto-and a body of fluorescent material associated therewith which consists in applying a highfrequency current greater than,

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