US2062959A - Electrical discharge device and electrode for same - Google Patents

Description

Dec. 1, 1936. R BARCLAY 2,062,959

ELECTRICAL DISCHARGE DEVICE AND ELECTRODE FOR SAME Filed Oct. 23, 1931 1751/ 5 fifleri 1375a rciqy Patented Dec. 1, 1936 Parana OFFICE ELECTRICAL $ISCHARGE DEWGE ELECTRODE FOB SAME My invention relates in general to electrical discharge devices and has more particular reference to a device for creating electrical discharges in an ionized gaseous field.

, hieretoi-ore, it has been considered impractical to employ certain gases, such as carbon dioxide and other chemically active gases, in devices of the character mentioned, and it has been the custom to employ relatively inert gases, such as 3a mercury vapor and the noble gases, neon, argon, crypton and the like, as the carrying medium for the discharge. These gases are not readily obtainable in commercial quantities and have to he produced artificially at considerable cost.

It is an important object of my invention-to make possible to use cheap, readily available gases as the carrying medium for the electrical discharge.

Another important object is to improve the performance and operating characteristics of '20 electrical discharge lamps generally, and particularly lamps employing neon, mercury vapor, argon, crypton, xenon, or other discharge conducting media.

Considerable difliiculty is at present encoun- 35 tered in the operation of lamps of the class described for the reason that after the lamp is operated for a considerable length of time, the gas, with which the lamp was originally filled,

, seems to evaporate and disappear. It is my belief that the electrodes, employed for creating the electrical discharges in the lamp, absorb, dissipate, or convert the gas in some manner, which is at present not explainable, and thus impair its discharge conducting character.

35 My invention embodies the provision of a new electrical conducting material particularly adapted for use in electrodes for discharge lamps, and I have found that this particular material, when used with the ordinary are carrying gases,

40 such as neon,crypton, mercury vapor, and the like, produces a discharge lamp having a substantially indefinite service life and the material moreover can also be used with chemically active gases, such as carbon dioxide, to produce a commercially operable discharge lamp, a result which has not been heretofore accomplished to my knowledge.

The production of the carbon dioxide discharge lamp in itself is new and results in numerous ad- 50 vantages not found in existing lamps of this general character. The carbon dioxide lamp emits a blue-white light, which is very easy on the eyes so that the lamp can be used for illumination without causing undue eye-strain. The light, produced by electrical discharge in carbon 5 dioxide, is, furthermore, a close approximation of the visible rays of natural sunshine and gives an unusually life-like appearance to all objects on which it is directed. For this and other reasons, the carbon dioxide discharge lamp has great value wherever natural illumination is desired, as for instance, in stores. where the colorof the goods must be accurately matched and determined to the satisfaction of a prospective customer.

A further object of my invention is to enable cheap, readily obtainable gases to be used in lamps of this general character.

Numerous other objects and advantages of the invention will be apparent from the following description, which taken in connection with the accompanying drawing, discloses a" preferred embodiment of the invention.

Referring to the drawing:

Figure 1 is a section taken through one end of a discharge lamp embodying my invention, the illustration showing the usual sealed envelope with electrode therein and the electrical connection extending from the electrode through the sealed end of the envelope for the purpose of connecting it with an external source of electrical power;

Figure 2 is an enlarged sectional view taken substantially along the line 2-2 in Figurel;

Figure 3 is a sectional view taken substantially along the line 3-3 in Figure 2; and

Figure 4 is a section taken substantially along the line 44 in Figure 3.

To illustrate my invention, I have shown on the drawing, one end of a preferably glass envelope I I of conventional construction provided with spaced apart electrodes l3 in the envelope. Only one electrode, however, is shown, since the other is or may be similar to the one illustrated. The envelope ll'may be made from a tubular glass member, the ends of which are sealed, as illustrated, at IS. The electrode I3 preferably comprises a cylindrical sheet metal body l1 configurated with an annular squeezed-in portion l9 intermediatethe ends of the cylindrical body and the material, forming the electrode, is flattened as at 2| upon one or more wires 23. The electrode is also preferably provided with a necklace 25 of glass beads, which encircles the body of the electrode by seating in the depression I! so that when the electrode is arranged in the tubular member H, the beads of the necklace will space the electrode centrally within the channel of the envelope.

The wires 23 extend outwardly through the sealed envelope and provide means for electrically connecting the electrode in an external circuit.

In my present invention, the envelope may be filled with any of the gases, which are now commonly used for creating an ionized path within theenvelope II and between the spaced electrodes I 3 thereof, that is to say, such gases as mercury vapor and the noble gases, neon, crypton, argon, or other media capable of being excited to sustain electrical discharge therein or the envelope may be filled with other gases, which heretofore have not been considered practical as carrying media for the electrical discharge. I particularly contemplate the employment of carbon dioxide as the carrying medium in the lamp of my present invention. The envelope II is therefore filled with carbon dioxide or other suitable gas or gases and I prefer to operate the device at a vacuum of 10-15 mms.

Heretofore, it has been considered impossible to produce a commercially satisfactory carbon dioxide lamp of the character described with the electrodes inside the envelope, for the reason that lamps, produced in accordance with the known practice, deteriorate extremely rapidly and fail in so short a time as to be useless for anything but experimental purposes. This extremely short life, it is thought, is due to the rapid oxidation, which occurs between the electrodes and the chemically active constituents of the gas in the presence of the heat generated in the electrodes by the electrical discharge.

It has been proposed to utilize carbon dioxide in discharge lamps by applying electrostatic pressure to the device from outside of the envelope. This, however, involves an enormous consumption of power so that lamps of this character are commercially valueless as a matter of simple economics. Furthermore, the discharge, produced by the external electrostatic application of power, is so feeble and the lamps flicker so as to be commercially useless.

My present invention contemplates the provision of a carbon dioxide discharge lamp having electrodes sealed in the envelope in the ordinary manner so that the electrical power is applied directly to the excitable medium within the envelope so that a continuous intense blue-white light, suitable for commercial purposes, is produced with an extremely low consumption of power. I

The electrodes l3 form perhaps the most important feature of my present invention. These electrodes are perhaps one-half the size of the commercial electrodes now employed in lamps of this general character and-are made of an electrical conducting material comprising an alloy of copper, with silicon and manganese, preferably in the following proportions by weight:

While these percentages give an example of my composition that has been found to give good results, I do not limit my invention to these exact percentages, as anyone skilled in the art-will be able to vary the proportions as may-be required.

The silicon constituent substantially inhibits deterioration or dissipation of the electrode by sputtering when subjected to electrical discharge currents while the manganese is desirable to render the alloy readily workable to shape the same.

My electrodes may be, and preferably are, activated, before they are assembled in the envelope II, by alternately heating and immersing them in a solution of a suitable butyl derivative, preferably butyl alcohol, or butyl acetate. in cellulose nitrate as a carrier. It is not, however, absolutely necessary to activate the electrodes and in this respect, among others, my electrodes are superior to the ordinary electrodes, which require activation as a prerequisite for successful operation, in accordance with present standards. It is however desirable, in certain instances, and depending upon the are carrying gaseous medium, with which" the electrodes are to be eventually used, to activate the electrodes. For instance, it is desirable to activate the electrodes when the same are to be used with mercury vapor, as in making the cold cathode ultra violet ray lamp illustrated and described as a part of my copending application Serial Number 589,563, filed October 19, 1931.

I have found also that general purpose lamps embodying electrodes made in accordance with the foregoing formula have a practically indefinite life when operated under ordinary conditions and when subjected to substantial overload conditions for the purpose of conducting comparative breakdown tests, devices embodying my present invention have from two to ten times the life of devices employing existing electrode forms.

It is thought that this unusual extension of lamp life is due to the fact that the particular alloy, which I have disclosed as a part of my present invention, is not chemically active in the presence-o1 gaseous mediums even when heated to the extent prevailing in lamps of the character described when in operation, while electrodes of the ordinary type re-act with the gases with which they are employed to either absorb the gas or to convert the gas into oxygen.

Among the numerous advantages of my present invention are the substantial extension of the operating life of electrical discharge lamps employing the gases now used commercially in lamps of this type; the possibility of employing cheap gases, such as carbon dioxide. successfully with the production of a new quality of light in the field of the electrical discharge illumination; and the resulting commercial advantages of being able to employ relatively cheap gases in discharge illumination.

It is thought that the invention and numerous of its attendant advantages will be understood from the foregoing description and it is obvious that numerous changes may be made in the form, construction, and arrangement of the several parts without departing from the spirit or scope of my invention, or sacrificing any of its attendant advantages, the form herein described being a preferred embodiment for the purpose of illustrating my invention.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is as follows:

1. An electrode of the class described comprising a copper alloy consisting of approximately 96% copper, 3% silicon and 1% manganese.

2. An electrode oi the class described compris- 5 ing a copper alloy 01' the following approximate formula:

Copper ....-..aibo ut 95.54% Silicon ..-about 3.06% lo Manganese about 1.20%

3. A discharge lamp comprising a sealed en velope containing a gas capable oi being excited

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