US2030445A - Gaseous electric discharge lamp device - Google Patents

Description

Feb.-ll, 1936. H. GOOSKENS GASEOUS ELECTRIC DISCHARGE LAMP DEVICE Filed NOV. 7, 1954 15 INVEPJTOR 9y zz z ATTORNEY Patented Feb. 11, 1936 GASEOUS ELECTRIC DISCHARGE LAMP DEVICE Henricus Gooskens, Eindhoven, Netherlands, assignor to General Electric Company, a corporation of New York Application November 7, 1934, Serial No. 751,953 In the Netherlands November 9, 1933 6 Claims.

The present invention relates to a gaseous electric discharge lamp device generally and more particularly the invention relates to such devices the gaseous atmosphere of which consists of or comprises the vapor of a relatively difficultly vaporizable metal, that is a metal the vapor pressure of which is less than 1 mm. at a temperature of 200 C.

In order to have an effective metal vapor pres- 10 sure in the device during the operation thereof,

that is, a vapor pressure such that the light emitted by the device is rich in rays characteristic of the metal vapor, the container of the device must be at an elevated temperature and a heat conservator, such as an evacuated jacket, which reduces the dissipation of heat from the lamp container, is useful in this connection. The vapor pressure in vapor lamp devicesis determined, in general, by the lowest temperature existing in the container and during the operation of the device the surplus vaporizable metal is deposited on the part of the container having the lowest temperature.

The object of the present invention is to provide means in a gaseous electric discharge vapor lamp device whereby the efiiciency and the useful operating life of the lamp device is increased. Another object of the invention is to provide a lamp unit comprising an efficient, long-lived gaseous electric discharge lamp device and a heat conservator for said lamp device. 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 invention comprises a heat source mounted in operative relation to the part of the lamp container which is at the lowest temperature during the operation of the device which heat source revaporizes such quantity of the metal deposited on said low temperature container part that the vapor pressure in the lamp device is increased above that pressure which Would exist in said lamp at the temperature 45 of said low temperature container part. Part of the vaporous material condenses again on said low temperature container part. The metal vapor is thus circulated and I have discovered that this circulation of the metal vapor increases the 50 efiiciency of the lamp device considerably and slows up the depreciation of the lamp device, that is, the intensity of the light emitted by the device diminishes very slowly during the life of the lamp device which, of course, increases the 55 useful operating life of. the device.

' tainer.

When a continuous circulation of the metal vapor is desired the heat source is mounted and regulated in such manner that while the lowest temperature part of the container is heated there by the temperature thereof still remains below 3 the temperature of the other parts of the con- When desired the vaporizable metal is heated intermittantly and locally. An anode of the lamp device is used as the heat source, when desired, said anode having such structure that the 30 temperature thereof increases when the operating voltage of the lamp device increases.

A heat conducting element extending from the anode to the vaporizable material is useful in transferring heat from said anode to said vaporizs able material. I prefer an anode of. wire, such as a wire ring of high melting point material, such as tungsten. The operating voltage of the lamp device increases when the vapor pressm'e falls below a certain value. The anode temperature thus 20 depends upon the vapor pressure and when the vapor pressure falls to the level at which the voltage between the electrodes increases the anode temperature is increased by the more intense electron bombardment thereof and the vaporizable 25 metal is heated to the vaporization temperature thereof. The vapor pressure is thus built up to the desired level and the desired operation of the lamp is resumed.

In the drawing accompanying and forming part 30 of this specification two embodiments of the invention are shown in which Fig. 1 is a front elevational, partly sectional view of one embodiment of the invention, and

Fig. 2 is aperspective view of one element of the 35 embodiment illustrated in Fig. 1.

Fig. 3 is a front, elevational View of another embodiment of the invention.

Like numbers denote like parts in all the figures. 40

Referring to Fig. 1 of the drawing the new and novel lamp unit comprises a gaseous electric discharge lamp device and a heat conservator therefor. Said lamp device comprises a bulbshaped container I having electrodes 3, 4 and 5 sealed therein, a starting rare gas therein, such as argon or neon, and a vaporizable material therein, such as sodium. The interior of said container I is divided into two chambers, a stem chamber and an electrode chamber, by the septum 2, such as a resilient chrome-steel or glass disc. The electrode 3 is the cathode and consists of a filament, such as a tungsten or nickel filament, wrapped around said first named filament, and a coating of electron emitting material. such as barium oxide, applied to said filaments. Said cathode 3 is wound in the form of a helix. Said electrode 4 is an anode and consists of a metal strip bent in the form of a ring. Said electrode 5 is another anode and is made of a thin wire, such as a tungsten wire, having a diameter of about 0.75 mm. Said anodes 4 and 5 are equidistant from said cathode 3 and are mounted on opposite sides of said cathode 3. The end of said container I has a protruding cup-shaped part 1 and an extension 6 of the anode 5 extends into said cup-shaped part 7. The anode 5 and the extension 6 thereof is made of a single piece of bent wire looped as shown in perspective in Fig. 2.

The leads 8 of the electrodes 3, 4 and 5 are of nickel, for example, and are surrounded over their entire length by tubes 9 of insulating material, such as magnesium oxide tubes. I prefer to allow a small space between said leads 8 and said tubes 9 so that the spaces on either side of the septum 2 are connected by long, narrow passages. These passages facilitate the manufacture of the gaseous electric discharge lamp device by making it possible to evacuate all parts of said container I through a single exhaust tube communicating with either of the spaces in said container I. After the lamp device has been operating a few hours the passages are closed by deposits of condensed metal vapor and the spaces on either side of the septum 2 are completely closed off from each other during the rest of the life of the gaseous electric discharge lamp device.

The welded joint between the anode 5 and the lead 8 therefor is surrounded by the insulating tube 9 so that said joint is protected from the gaseous electric discharge during the operation of the lamp device.

The container I has a starting, rare gas therein, such as argon or neon, at a pressure of approximately 1 to 10 mm. and a quantity of one or more relatively diflicultly vaporizable metals, that is a metal having a vapor pressure of less than 1 mm. at a temperature of 200 C., is introduced into the part of said container I surrounding said electrodes 3, 4 and 5. Sodium, cadmium, thalium, magnesium, potassium, lithium and zinc are examples of metals having such pressure at this temperature. When the vapor of such metals is at an effective pressure in said lamp device the light emitted by the device is rich in rays characteristic of the metal vapor. In the embodiment of the invention illustrated in the drawing the vaporizable material is sodium.

When desired the anode leads are electrically connected so that are discharges take place simultaneously between said cathode 3 and each of the anodes 4 and 5. When the lamp device is operated as a rectifier on alternating current the anodes 4 and 5 are connected separately to the alternating current source.

Said container I is surrounded by a doublewalled glass jacket I0 having the space between the walls thereof evacuated and which reduces the dissipation of heat from the walls of said container I. The container I and the jacket I0 are both equipped with bases, of insulating material when desired, which frictionally engage with the socket II. A resilient heat insulating, ring I2 consisting of a coiled spring covered with asbestos, for example, is interposed between said container I and the inner wall of said jacket I0 and is located at a part of said container I. adjacent said septum 2. Said ring I2 closes off the space surrounding the part of container I enclosing said electrodes 3, 4 and 5 from the ambient atmosphere of the lamp unit.

The structure of the lamp unit is such that the protruding part I is at a lower temperature than the other parts of the lamp device which form the enclosing walls of the space about the electrodes 3, 4 and 5. While this result may be obtained in many Ways, as disclosed in co-pending application Serial Number 750,713, filed October 30, 1934, the inventors being Gilles Holst and Willem Uyterhoeven, in the embodiment illustrated in Fig. 1 of the drawing this result is obtained by mounting the anode 4 closer to the septum 2 than the distance between the anode 5 and the end of container I. The upper portion of this part of container I is thus heated to a higher temperature by the discharge between said electrodes 3, 4 and 5 than the lower portion of this part of container I. The protruding part I, which is at the greatest distance from the discharge, is at the lowest temperature during the operation of the lamp device and deposits of condensed vapor take place in said part I.

The wire anode 5 is of such diameter that when the vapor pressure in the lamp device and the arc discharge voltage are at values such that the lamp device operates at its maximum efiiciency the temperature of said wire anode 5 is relatively low and the wire 6 conducts very little heat to the solid sodium deposited in the cup-shaped part I of the container I. When the vapor pressure diminishes to the extent that the arc discharge voltage increases the temperature of the anode 5 increases as pointed out heretofore. The heat conducted by said wire 6 from said anode 5 to the sodium in said cup I is thus increased and the sodium is heated to the vaporization temperature thereof and vaporizes. The vapor pressure is thus restored to normal and normal operating conditions again exist in the lamp device. The above described structure and operation of the lamp device is not only advantageous during the operation of the lamp device but also is advantageous in the starting of the lamp device since during the starting period the vapor pressure is rapidly raised to the effective pressure thereof and the lamp device emits an intense light shortly after it is started into operation.

The embodiment of the invention illustrated in Fig. 3 of the drawing is similar in all respects to that shown in Fig. 1 except that in this embodiment the anode 5 is similar in structure to the anode 4 and both said anodes 4 and 5 are connected to and supported by the said current lead. A small heating element I3, which is an electric resistance, is connected to the anode 5 and to one of the leads of cathode 3. The end of container I is substantially conical in shape and the heater I3 is mounted closely adjacent the conical end. A coating I4 of a heat conducting material such as graphite, which increases the radiation of heat from the coated portion of said conical part is applied to said conical part. The coated portion of the conical part is at the lowest temperature of any part of the electrode chamber of said container during the operation of the lamp device. When the sodium vapor condenses at the coated container part the condensed sodium is still suificiently liquid to flow down to the part of said container heated by the element I3 by which it is revaporized. Continuous circulation of the sodium vapor thustakes place which increases the efiiciency and the use:- ful life of the amp device.

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:-

l. A gaseous electric discharge lamp device comprising a containe electrodes sealed therein, a startinggas and a quantity of vaporizable material therein, means for maintaining a part of said container at a lower temperature than the other parts thereof and a heater mounted in said container adjacent the lowest temperature part thereof.

2. A gaseous electric discharge lamp device comprising a container, electrodes sealed therein, a starting gas and a quantity of vaporizable materialtherein, means for maintaining a part of said container at a lower temperature than the other parts thereof and a heater mounted in said container adjacent the lowest temperature part thereof, the temperature of said heater being controlled by the discharge current between said electrodes.

' other parts thereof, one of said electrodes being an anode the temperature of which is responsive to changes in voltage inthedischarge between .a wire ring anode the temperature of which is responsive to changes in voltage in the discharge between said electrodes, and means to conduct the heat from said anode to the vicinity of the lower temperature part of said container.

5. A gaseous electric discharge lamp device comprising a container, electrodes sealed therein, a starting gas and a quantity of vaporizable material therein, means for maintaining a part of,

said container at a lower temperature than the other parts thereof, said electrodes comprising two anodes and a cathode and a heater mounted in said container adjacent the lowest temperature part thereof, said heater being a resistance 'connected in series with one .of said anodes and said cathode.

6. A lamp unit comprising in combination a heat conservator and a gaseous electric discharge lamp device comprising a container, electrodes sealed therein, a starting gas and a quantity of vaporizable material therein, .means for maintaining a part of said container at a lower temperature than the other parts thereof and aheater mounted in said container adjacent the lowest temperature part thereof.

HEI lRICUS GOOSKENS.

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