US1919933A - Gaseous electric discharge device - Google Patents

Description

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I GASEOUS ELECTRIC DISCHARGE DEVICE Filed Jan. 12. 1933 200 Candle mower Ne. 53 W A .50-- l I l i I g I I I 1 Gqs pre sure (nun) 0'- 0.5 1 1.5 2 2.5- 3 3.5 v

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ATTORNEY I Patented July 25, 1933 UNITED STATES PATENT OFFICE C WILLEM DE GROOT, OF EINDHOVEN, NETHERLANDS, ASSIGNORTO GENERAL ELECTRIC COMPANY, A. CORPORATION OF NEW YORK G-ASEOUS ELECTRIC DISCHARGE DEVICE Application filed January 12, 1933, Serial No. 651,385, and in the Netherlands December 24, 1931.

The present invention relates to gaseous electric discharge devices generally and more particularly the invention; relates to such devices the gaseous atmosphere of which comprises a metal vapor.

It has been proposed to use gaseous electric discharge devices of the above type having a cathode which is electron emitting when heated and a gaseous atmosphere comprising a rare gas and sodium vapor as a source of illumination. Various ases such as argon, crypton, or xenon have een used as the rare gas constituent of the gaseous atmosphere heretofore. Applicant has found that the use of such gases-in an electric arc discharge lamp device is attended by many disadvantages. In the case ofargon, for example, the light emitted by the lamp "device after the arc discharge starts and before the .sodium vapor, generated from the solid sodium by the heat of the electric arc discharge conducted between the electrodes by the' argon gas, is at suflicient pressure to participate in the arc discharge us of no practical value for illuminating pur- The object of the present invention is to provide an electric discharge lamp device having a gaseous atmosphere comprising sodium vapor which emits sufiicient' light to be of practical value for illuminating purposes immediately on the start of the gaseous electric discharge. 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.

The invention attains its objects by using neon as the rare gas constituent of the gaseous atmosphere. Such a lamp device is not only useful as an illuminating means immediately on the starting of the are discharge, but operates moreefiiciently and the light emitted therebyhas a wider spectrum band than prior devices using sodium vapor alone, or a mixture of sodium vapor and gases other than neon since theneon spectrum supplements the monochromatic spectrum of the sodium light during the operation of the device.

' The invention will be readily understood by an inspection of the accompanying drawing and a perusal of the following detailed description thereof.

Fig. 1. of the drawing is a schematic representation of an electric arc discharge lamp device and Figs. 2, 3 and 4 are curves showing the relative values of various gases used in the type of electric arc lamp device illustrated in Fig. 1 when operated on direct current.

The electric arc discharge lamp shown in Fig. 1 has an approximately spherical container 1,.having a press 2 which projects toward the outside of said container 1. The current-supply leads iare sealed into this press 2 and are connected to the electrodes 3 and 4 of the discharge device. The elecv trode 3 is a coiled; cathode which is covered with a layer of earth-alkali oxide and is electron emitting when heated. Two plate-shaped anodes 4 are located a dis tance of approximately 15 mm. from said cathode 3. The container 1 has a as filling consisting of neon at a pressure 0 '2.5 mm. 75'

at room temperature. A quantity ofsodium. is located in said container 1 and the vapor thereof participates in the are discharge during the operation of the device. In order to diminish the heat radiation from the container 1, said container 1 is enclosed in an envelope 5 having a press 6 into which theicurrent-supply wires of the electrodes vapor participates intensively in the discharge whereby a very strong light is emitted by the discharge lamp device. The temperature of container 1 is high and the pressure of the sodium vapor is that which exists .at a temperature of 200 to 300 de grees C. At this pressure,"the discharge 'lamp deviceis at its maximum efiiciency.

The electric discharge between said elec- 100 trodes 3 and 4 is an arc discharge without a positive'column. The starting voltage is 17 v., and the operating voltage of the discharge is 13 v. I v

An impedance, such as a resistance, choke coil, or leakage transformer, is connected in series with the discharge device, acting as a ballast to steady the arc discharge. Such impedance has not been shown for purposes of simplicity.

The structural details of the lamps are more fully shown and described in my copending application Serial Number (351,38 filed January 12, 1933, to which reference is made for the complete disclosure of said lamp devices.

Fig. 2 gives the number of international candle units of the light emitted by discharge devices of the above type as a function of the gas pressure, when such devices have a neon filling, an argon filling, a krypton filling, or a helium filling. The power consumption (including the power-required for heating the cathode 3) is approximately the same for the different gas fillings; that I is,-53 w. for the. neon filling, 57 w. for the argon filling and 58 w. for the krypton filling. The pressure of the gas at room temperature is expressed in millimeters.

The curve A gives the relation when neon is used, while curvesB and C give the relation when argon and krypton respectively are used. The figures show very clearly that the light emission of a discharge device filled with neon isconsiderably greater than'that of a discharge device filled with argon or krypton. Helium gives more unfavorable results. In Fig,. 2, for instance, the. line D- 'glves the 'candle'*'power of a sodium vapor lamp filled with helium. Although the power consumption of adischarge device- .filled with helium is somewhat smaller than that of asimilardischarge device having a filling of neon, argon, or krypton, representcd by. the'curves A, B, C; namely, 44 w.,

a comparison of these curves shows that the efiiciency is considerably smaller than in the case of a discharge device filled with neon, even when the-lower energy consumption is taken into account.

The curves A, B, C, show a maximum which is not shown in the ease of curve D. The maximum of curves B and C is rather sharp, as indicated by dotted project-ion lines from the knee of the respective curves to the X axis in Fig. 2. The maximum of curve A, however, is not so sharp,- as shown by the flatness of that curve on each side of its projection linein Fig. 2. The importance of these relations, as shown by the curves in question, is considerable, because the opti;

mum value of the gas pressure of a neon filling, i. e., the pressure which produces the highest temperature ofthe vapor component of the filling, within practical limits, is not and krypton pressure which is advantageous since a relatively large quantity of neon must be placed in the container 1 which gives a longer life to the device as this large quantity of neon does not disappear as rapidly as the smaller quantities of argon and krypton.

In Fig. 3, a few more curves E, F, G and H of discharge devices with containers of other dimensions are shown. The diameter of the container used for, determining the curves of Fig. 2 was 50 mm., the diameter of the container of the device used in determining the curves E and F was 60 mm. and the diameter of the container of the device used for determining curves G and H was 45 mm.

Line E is for neon filling and a power consumption in the discharge device (including the power for heating the glow cathode 3) of 90 w., while curve F applies to an argon filling and a power consumption of w. Curves G and H were determined by a power consumption of 53 w. and a gas filling of'neon or argon respectively. This figure again shows clearly that the use of neon has great advantages.

ture and thesurface is measured in square centimeters. The figure shows that the neon pressure should preferably be less than 4 mm. at room temperature. The figure further shows clearly that the optimum pressure depends on the size of the surface according to alinear function. Figs. 2 and -3 show that the pressure of the neon may be somewhat higher or somewhat lower than the. optimum value without any great disadvantage.

As the curves A, E and G are rather flat at the maximum, a change in the neon pressure around the optimum value causes only a slight decrease in the light emission. The favorable values of;the pressure are'located in a field above and below the curve K, as shown in Fig. 4, represented in the area limited by the straight lines L and M. The straight lines L and M are represented by the functions 1.14 10' XQ respectively where p is the pressure in mm. and Q, is the size of the surface of the bulb in square centimeters. It is, therefore, preferable that the neon pressure lie between the maximum and minimum values given by these equations.

While I- have shown and described and have pointed out in the annexed claims certain novel features of the invention, it will be understood that various omissions,'substitutions and changes in the forms and details of the device illustrated and in its use and operation may be made by those skilled in the art without departing from the broad spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is 1. An electric discharge'lamp devicecomprising a container, electrodes sealed therein, a gaseous atmosphere therein comprising sodium vapor and neon, the gaseous electric discharge between said electrodes being an arc discharge, and means for maintaining said container at a temperature from 200 to 300 degrees C.

2. An electric discharge lamp device'comprising a container, electrodes sealed therein, a gaseous atmosphere therein comprising sodium vapor and neon, the neon pressure being less than l mm. at room temperature,

' the gaseous electric discharge between said electrodes bein an arc-discharge and a heat retaining envelope surrounding said container and spaced therefrom.

3. An electric discharge lamp device comprising a container, electrodes sealed therein,

a gaseous. atmosphere therein comprising sodium vapor and neon, the pressure of the sodium vapor being that which exists at temperatures between 200 to 300 centigrade during the operation of the device,

and the gaseous electric discharge between from l te 3.5 mm. pressure at room temperature in combinaton with sodium va or.

VVILLEM DE GB 01.

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