US1842624A - Electron discharge tube - Google Patents

Description

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ELECTRON DISCHARGE TUBE Filed Feb. 25, 1928 INVENI.

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MUNTFURD MORRISON, U UHIUAGO, ILLINOIS, ASSIGNOR, BY MESNE AS$IGNMENT$, TU

'WESTINGHUUBE ILAMPCOMPANY, A UORPORATJION 0F 1 lElLlEUTRON HDISCHGE WEE Application filed Itebrnmy as, 19%. Serial lilo, twtfillt The present invention relates to luminous discharge tubes of the gaseous ionization type, such as used for illuminated advertising signs and the like. This invention is constituted of some of the elements disclosed in my co-pending application, Serial 566,961, filed June 9, 1922, and is a part thereof.

Among the objects of my invention are; to provide a method of exhausting and filling 1a luminous discharge tubes such as to eliminate trapped foreign gases which are responsible for variation 1n intensity as well as variation 1n color in luminous discharge tubes; to provide means for stabilizing the of the lead-in wires into the vacuum chamber such as to prevent deterioration of the lead-in wire and leakage of gas at this point.

Fig. 1 represents a completed tube showing an embodiment of my invention after the tube has been sealed ofi of the apparatus used in connection with producing it. Fig. 2 is a complete embodiment of my invention showing the method of pumping the tube as well as the method of filling it, and Fig. 3 is an enlarged cross-section of one of the-electrodes and electrode chamber.

in the prior art, the methods of evacuating and filling luminous tubes of this class have invariably been to make one sealing-in connection to the tube and pump the tube from this sealing-in connection, as well as after the tube has been pumped to allow the gas which fills the tube to enter the evacuated chamber of the structure at the same opening.

This, I have discovered, accounts for much of the erratic behavior of these tubes, their short life as well as for the fact that the tubes have to be seasoned by a long continued operating process which, in some cases, has to.

be continued tor several days before the tube will assume its normal color and operating characteristics.

l have discovered that in these methods used in the prior art, involving the above process referredto, that there is always a certain amount of residual gas trapped within the tube, and it is this trapped gas that is responsible for the variation in intensity oil the tube, as well as the variation in color, and this aging process, l have discovered, is merely a means which tends to get foreign gas which is left into the tube.

In my invention ll totally obviate this seasoning process by a method of filling the evacuated chamber in such a waythat it contains only the desired gas, and no foreign gas, hence all the diificulties experienced with the prior art processes are eliminated.

In the prior art tubes, electrodes have been always employed having a multiplicity of firing points which either comprise sharp points or sharp edges. Cylindrical pieces have been employed with holes drilled in them producing sharp edges at the boundaries of the cylinders, wires having points have been utilized, and in some cases electrodes constructed so that the sharp edges of the electrode was greatly increased.

l have discovered, as disclosed in my above referred to application, that a great deal of the erratic behavior in electron tubes is due to these sharp edges or points which concentrate the electrostatic field at points, causing excessive ionization where it is not desired.

in the present invention, I employ the electrode disclosed in my above mentioned application in such a way that the discharge is llili IllO ill

rapid changes in the gas pressure, shortening the life of the tubes. In my invention I have provided means for stabilizing the gas pressure, as well as the gas mixture in the 5 active part of the tube, thereby quite obvious ly increasing the tube life. A

Having described my invention in general terms, reference may now be had to the accompanying drawings.

Fig. 1, lie an elongated gas chamber of glass or other suitable material on to the right end of which is sealed an enlarged chamber 2'havi'ng seal-in wire 3 and an electrode 4, of a particular construction herein after described. On the left-hand of the ered due to operation.

In Fig. 2 is shown the completed tube of Fig. 1 in process of production. Similar parts are similarly numbered. 9 is an evac uating pump connected to a piece of tubing 10, which is sealed on to the chamber of the luminous tube at 11, by which connection the entire contents of the chamber of the luminous tube may be evacuated. Tubing 10 is provided with a stop cook 34. 12 is a bottle containing a gas or vapor which is to be in-' troduced into the luminous tube. 13, 14 and 15 are stop cocks whichare used to measure the amount of gas admitted into the lumi nous tube, as well as to disconnect the bottle 0 12 from the evacuated chamber. The bottle 12 is connected to the lumindus tube at an opening remotel disposed from 11 and at 35.

' 36 for measuring 315s an additlonal bottle containing a gas or vapor, and provided with stop cocks 32 and the gas therefrom. The on to the tube line of the bottle 31 is seale gas bottle 12 at point 33.

16's a source of alternating electromotive I force which is fed by leads 17 and 18 through .50 switch 19 to primary 20 of step-up transformor 21, w 'ch; by means of induction to secondary supplies high voltage 'to the electrodes 4 and 6 of the luminous tube by means of leads 23 and 24.

In Fig. 3, similar .parts of Fi s. 1 and 2 are similarly numbered. Electro e 6 of Fig. 3 presents a rounded contour at all points such as 25, 26 and 27, and the like. The leadin wire 7 is sealed into a glass'tube 28 over which the electrode 6 is placed, as shown at 29. This construction shields the lead-in wire at 30 from the electric field of the discharge,

/ and prevents its deterioration at this point,-

as well as preventing the concentratiouof field due to the'small lead-in wire, in addi-.

tion to which this construction greatly strengthens the supporting structure of electrode 6 such as to prevent its breaking off or being injured in transit.

As disclosed in my parent application, such an electrode prevents the concentration of electric field at or about the electrode. The local concentration of electric field in adischarge tube sets up local heating, which tends to liberate gas from the electrode, which in turn destroys the stability of the tube by changing the gas content of the discharge chamber. With this electrode under operation, the entire field adjacent uniformly glows with discharge, showing no concentration of field and no concentration of luminous intensity at or near any particular part of the electrode.

The process of evacuating and filling tubes to operatein accordance with my invention may be understood by reference'to Fig. 2.

First, the stop cocks 13, 14 and 15 are turned to their 011' position and the evacuating pump 9 is set into operation and the gas is removed from the total chamber under evacuation by means of the pump and any other such .accessory means as heating the glass envelope, heating the electrodes, and

operating the tube under electrical discharge by means of transformer 21. These accesthe electrodes and glass parts more com letely of gas than would be otherwise possi le.

Aa'fter chamber 1 has been sufliclently evacuated, stop-cock 34 is closed, stop cocks 13 and or 14, depending upon the conditions, are opened, admitting some of the gas or vapor content in bottle 12 into the tube betweenusually to theopposite end 0 the tu end occupied by chamber 5, and that by no method or means may the gas thus trapped be evacuated by pump 9. By repeated processes of pumping and allowing the gas to flowin at the same opening 11, results in pockets of gas usually trapped along the tube which, under operation, very distinctly shows streaks of difierent colors due to the two gases being trapped at difierent points. By operating these tubes under long periods and going through other operations, the gas sometimes becomes sufliciently well mixed that the entire tube may, after several daysoperation, have all the same color and assume a stable state of o eration. However, some tubes never sory devices are merely means for ridding residual "gas in the tube 1 and ushiniiat oviln in t e.

. acquire this state and always show pockets 0L.

- I no variation gas in the tubes.

ttl

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teeaeee Tn some cases T find it desirable to wash out the tube 1, by gases from bottle 31, through stop-cocks 82 and 36, before admit ting gas from the bottle 12 into the tube 1.

New by the processes which I have discovered, and that is by evacuating from one end of the tube, namely at 11, and allowing the gas to enter at the opposite end of the tube, namely 35, T can by one or more operations completely entrude all the residual gas from the left-hand end of the tube to the right end of the tube 2, and finally outthrough the pump at 11. Tn some cases ll utilize the stop coclr 84: for cutting the pump 0d at times, as a matter of practicability in the process of producing the tube.

A tube produced under this process, having no foreign gases present, does not require to be seasoned and does not require any process of destroying the gas or thoroughly mixing it so as'to obviatedifferent colored gas discharge sections.

A'tube thus constructed operates from the very beginning of its life with a perfectly uniform discharge throughout the entire luminous portion, and with entire absence of strealrs or other related undesirable characteristics. The great time cost in trying to rid the tube of this gas is entirely eliminated. Tn addition to this, the tube burns with a brilliance not attained by tubes constructed b the prior art. The tube has a long stable life because there is no concentration of electric fields at the electrodes A and 6. @ince the discharge is perfectly uniform over these electrodes, they work at a uniform temperature and, therefore, give uniform behavior. Because the original air is entirely absent from the tube, there is substantially no oxygen present to attach the electrodes and change their surface characteristics, and, therefore, change their operating behavior. Therefore, the tube operates in a stable condition for a greater period of time than do tubes of the prior art. The non-focusing construction of my electrode, eliminates puncturing of the glass tubes due to the cathode ray stream.

After the evacuating and filllng process is complete, the tube 1 is sealed 0d at points 11 and 35, and results in the finished tube illuset in lEig. l... The chamber 8 shown in r. l goes-into operation when the gas pressure in the luminous tube 1 changes for any reason. This chamber 8, being of large'voluinetric capacity, supplies gas to the luminous tube 1 on the pressure therein dropped, thus preventing the tube from going out due to low gas pressure, early in its life.

it will be appreciated that chamber 8 is outside of the discharge field of the luminous tube and, therefore, the electric discharge in the said tube has no effect on the gas in chamher 8, and, therefore, any gas change ncountered in tube 1 due to electric discharge therein does not affect the gas in chamber well as to the length of life of a luminous dis charge tube constructed according to my invention.

In the specification and claims, the word gas is used to mean either gas or vapor, in any or all senses of both words.

Claims:

1. A gaseous conduction discharge device comprising an enclosing envelope, an inert gas filling and a plurality of electrodes, at least one of said electrodes having means to distribute the electrical discharge uniformly over the electrode surface and a sealedin lead-in conductor constituting a support for said electrode.

2. A gaseous conduction discharge device comprising an enclosing envelope, an inert gas filling and a plurality of electrodes, at least one of said electrodes having surface characteristic means to cause an electrical discharge to radiate with substantial uniform intensity over its entire surface and a sealed-in lead-in conductor disposed internally of said electrode and constituting a support therefor.

3. A gaseous conduction discharge device comprising an enclosing envelope, an inert gas filling and a plurality of electrodes, at least one of said electrodes being substantially free of points of electric flux concentration over its entire active surface and a sealed-in lead-in conductor disposed internally of said electrode and constituting a sup-' port therefor.

A. A gaseous conduction discharge device comprismg an enclosing envelope, an inert gas filling and a plurality of electrodes, at least one of said electrodes being substantially curvilinear over its entire active sur face and provided with a sealed-in lead-in conductor disposed internally. of said elcctrode and constituting a support therefor.

5. A gaseous conduction discharge device comprising an enclosing envelope, an inert gas filling, a plurality of electrodes, and

means to uniformly distribute the electrical 7. A gaseous conduction discharge device comprislng an enclosing envelope, an inert gas filling, a plurality of electrodes, and means to uniformly distribute the electrical discharge over the entire active surface of said electrodes said means comprising a surface shaping of said electrodes to eliminateall points of electric flux concentration thereon provided with a sealed-in lead-in con-. ductor disposed internally of said electrode and constituting a sup ort therefor.

Chicago, Illinois, Fe ruary 23, 1928. I 1 MONTFORD MORRISON.

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