USRE18798E - Discharge tube - Google Patents

Description

April 1 1933- c. J. R. H. VON WEDEL Re. 18,798

DISCHARGE TUBE Original Filed March 7, 1928 23251 ll'romwa w.

Reiesued Apr. .18, 1933 UNITED STATES PATENT o FIcE I CARL J. B. H. m ml... NEWARK, NEW JERSEY, ASSIGNOR, BY MESITE ASSIGN- 1 mas, TO ELECTIONS, INC, A CORPORATION OF" DELAWARE DISCHARGE TUBE Original 10. 1,807,140, dated Key 86, 1981, Serial No. 850,715, fled March 7, 1929. Application for reillue filed June 18, 1881. Serial lo. 544,250.

V The present invention relates generally to discharge tubes,- and more particularly to structures and mounting arrangements for such tubes.

A particular object of the invention is to provide a discharge tube having a usefully long discharge ath for desired purposes such as colored light tubes for advertising effects, ultra violet ray tubes, and the like, and yet can be connected for operation into a single electrical socket, such as the usual lamp sockets of lighting circuits.

A further object is an arrangement per-- mitting close physical association of necessary discharge electrodes so shielded that the desired operating discharge can be directed over a desired long path and prevented in short direct paths necessary to the particular unitary construction herein contemplated.

The invention will be further understood by reference to the figures'of the accompanying drawing in which like reference numerals represent like parts in so far aspossible in the several figures.

Fig. 1 shows a discharge tube adapted for alternating current operation with electrode,

. shield and mounting arrangements embodying features of the invention.

Fig. 2 is a side view in section of the tube portion of Fig. 1 showing in further detail the electrode and shield arrangement.

Fig. 3 shows a discharge tube having the general features of the tube of Fig. 1, but modified as to the electrode arrangement with cooperating modifications in the supply circuits.

Referring to Fig. 1 a circular or otherwise suitably shaped tube 1 of glass or other suit able materal for forming va discharge path is shown to include two discharge electrodes 2 and 3 erected on a stem 5 encompassing electrode lead-in wires usual to suchtubes, the two electrodes being shielded from each other by a shield 4 'so as to prevent a direct discharge between them, thus confining the desired discharge to and around the long and unobstructed path embraced by the tube.

' stem and welded or otherwise suitably atstructure. v

The electrodes 2 and 3 are indicated as of thetype adapted to emit electrons as by heating with a current passed through the and the like purposes, and gas-filled tubes including mercury or like metallic vapors for producing ultraviolet rays, it is particularly desirable that an electrode structure that will withstand ionic bombardment be chosen for 2 and 3. For this reason a structure comprising a coating of electron emissive compounds, of the nature disclosed and defined in application Serial Number 196,996 filed in the U. S. Patent Oflice on or about June 6, 1927, by Freidrich Meyer and Hans Joachim Spanner, or layers of electron emissive compounds, of thenature disclosed and defined in application Serial Number,

251,736 filed in the U. S. Patent Office on or about February 3, 1928, by 'Hans Joachim I Spanner and myself as joint inventors, as

the emissive material on a suitable metal core or wire is most suitable, as such compounds have been found capable of resisting ionic bombardment most effectively.

The shield 4 may be made of non-conductive material such asmica, or non-conductive material having a metallized surface,

such as mica having a deposit of getter inaterial, as magnesium, resulting from the deposit of'su'ch material on internal parts of a tube accompanying theusual degassing processes with getter materials; or ma be a conductive material, such as nickel, mo ybdenum, or other suitable metals. The shield may be mounted on the glass stem 5 by means of an upright 24 inserted into the body of the glass tached to the shield 4.

By reference to Fig. 2, it isseen that the shield 4 is made to fairly closely fill the crosssectional area of the lowerportion of tube .1 and .thefupright portion of that part of the" tube surrounding the stem 5,'-bu't the shield is not shown to extend all the way to the bottom of the stem 5. It isnot necessary that the shield have an absolutely tight fitat the Walls of the tube or extend to the bottom" of the stem portion of the tubeto prevent a discharge directly between the electrodes 2 and 3 becausedn operationtheshield, the

glass walls thereabout, and the s'tem'5 collect on their surfaces electrical charges by reason of the electrons in the tu'be,'which elec trical charges fe ve the effectof neutralizing ionic effects necessary to maintai'ning the dis'-' charge. For example, if a discharge attempts to take place between electrodes 2 and 3 by tralizing ions to thereby prevent'the'suc'cessfulestablishment of a discharge by 'way of suchpath. The conditions of operation however,determine the closeness of fittingnecessary for the shield, it being obvious that under conditions of employment of high disventlng a discharge than under conditions of lower potentials. In the case of very high potentials, twoshields paralleling each other would be more effective than one shield, and additional protection may be had by applying to these shields suitable potentials from outelectrons in the tube, for it may bethat a a charge so, collected will havea potential so high as to interfere with the desired operation of the tube as a discharge device by way of the long path, and the connection shown would. permit. of leakingofi the charge. For example, the lead wire is shown connected tothe mid-pointof the primary winding 8, though it may be connected to other points on this winding or other sources of potential to determine-the rate of'leaking away of an internal charge.

The tube 1 is shown mounted in a base caslamp screw plug 12 employed in connection 'with the usual lighting socket. The base cas-' ing is shown to include ana'lternating current transformer having a primary 8 and secon- 6 daries 6 and 7, which secondaries determine way of the path under the shield, the electrl cal charges accumulated on the shield, stem and glass walls'of "that portion of the tube surrounding the stem, have the efiectxof neu- 'charge potentials more difficulty is had in prev charge collected thereon by reason of thev as desired, or connected through a resistance ing 11 to which is attached the usual electric mass the potential of the heating currents of electrodes 2 and 3. The iron core required by such a transformer can well be shaped to fit into-"a circular arrangement off base, or other suitable'for'm, and carry thereon the neces-. sary primary and secondary windings. The

only energy that the transformer need handle is that required for heating the electrodes, and a few watts suflice for this purpose, so

that the transformer and windings can be simple afiairs of very fine wire.

The resistances 9 and 10 are inserted in series with a supply circuit leading to the electrodes 2 and 3, so that when a discharge takes place between these electrodes these resistances are in series with the discharge path, and by selecting these resistances of suitable values they determine the amount of 'current involved in the discharge. These resistances may be inserted inside the casing 11 wound in suitable form and on suitable structures to bring within the casing a sufficient length of resistance wire to obtain the. needed amount of resistance. However, there is necessarily some heat generated in these resistances which must be satisfactorily dissipated. One satisfactory way of. accomplishing the result would be to make the easing 11 of ,a, double wallkh'aving sufiicient spacing between the walls to permit of winding 'the resistance wire exteriorly of the inner wall and interiorly of the outer wall,

which arrangement is shown more in detail in Fig. 3. As a further means of" dissipating heat the outer wall may be provided with corrugations or cooling ribs in manner and of construction well known in the general practice of heat dissipation effects, also shown more in detail in Fig.3 I I Lead-in wires for energizing the primary winding 8' and energizing 'the' electrodes 2 and 3 by way of resistances 9 and 10 connected'to center points in windings 6 and 7 are indicatedas suitably connected at points 13 and 14 of; the screw plugarrangement 12 in a manner already well known in electric lamp practice. 7

The arrangement shown can be inserted into the usual light socket, so that closing the switch or pressing the'wall button usually associated with lighting systems will, in the one operation, permit of heatingthe electrode wires 2 and 3, and at the same. time apply a difierence of potential between these electron emitting electrodes, and since the discharge cannot take place in the short interval of separation because of the shield 4, a discharge is set up between these electrodes by way of the long path around the tube,

.resulting in the desired light or other effects sought from such a discharge.

The electron emitting electrodes have the effect of substantially eliminating the usual cathode drop present in such tubes, leaving the resistance of; the discharge path and theanode drop as the resistances to' be overcome .able from usual commercial circuits.

Since the two electrodes 2 and 3 are elec tron emitting, the arrangementioperates most readily with alternating current, the electrodes acting alternately as cathodes and anodes, and also permit thestarting of the new discharge at each half cycle 40f alter- 'nating current early in the ,building-up of the potential of each half .cycle, a feature most desirable in eliminating flicker effects common to usual tubes wperated by an al- =ternating current source.

"The arrangement in Fig. 3 is similar to that ,in Fig. 1 in thefeatures permitting emplo ing the tube in connection with asingle soc et. The arrangement differs from :that of Fig. 1 in providing for electrodes 17 and 1,8 which are normally cold, but are heated 'for :starting operation and in part during operation by an ionic bombardment between the main electrode 17 and'auxiliary electrode 19 and main electrode 18 and corresponding auxiliary electrode (not shown).

As in the case of Fi 1,, resistances 9 and {10 are connected iniseries with the main discharge path to limit the operating value of the discharge current to a desired degree, a part of the total resistance being shown as resistance winding 9' in .series with resistance 9 wound between the inner and outer walls of 'thecasing 11, and resistance winding 10' in series with resistance 10 also wound between the inner and outer casings. Of course all of the resistance in each circuit may be wound either within the casing or within the space between the walls, and the the-casing 11 indicate one aid .to dissipating same may be done with resistances 15 and I6. Cooling flanges or ribs on the outer wall of heat generated in the resistances and other elements within the casing.

There .are also included resistances 15 and 16 in series with each of the auxiliar discharge paths between the main electro es 17 and 18-and the corresponding auxiliary electrodes. These resistances 15 and 16, in usual construction, will be much larger in resistance values than resistances 9 and 10,- both because of the proximity of the auxiliary electrodes to the main electrodes and because normal operation will not require as large an auxiliary discharge for starting and heating purposes as is required in the main discharge. A ain, the starting discharge may require a airly large current, but which is notneeded once starting has taken place and the main discharge is operating to provide the elecbetween said electrodes are con trodef heating. The arrangement shown so connects the resistances 15 :and 16 withrelation to the main discharge circuit .and'ithe resistances 9 and 10 therein that once tithe main discharge has taken place, the current in zthe auxiliary discharge paths is limited,

all=as more fully explained in my copending application, Serial No. 254,921, filed ill-sebruary 17, 1928. Y a

In Figs. 1 and 3 the inleadwires "the main and auxiliaryelectrodes are indicated as surrounded byasmallglass tubes or other suitable insulatin material 20, this to vent destructive Q ischargesimpinging these more or lessffragileelements of the at rangenient. 1 i

Because of the alternating current former arrangement .inFig'. 1, at tube 11'- rangement so constructed can only be uperated with alternating :zcurrent. 'The 31- I rangement in Fig. ;';3 of operatilfi with both alternating rand direct current. operated with direct obviously one of the main electrodes: permanently acts as a cathode and the other .as :an anode. The use of resistances only in arrangement of Fig. 3 simplifies-the of including all of the required control "elements within a :single simply constructed 1. A discharge tube a single stem portion, a stem insaid portion, a air of electrodes erected on said stem, a laol ow toroidal envelope mounted upon said stem portion and forming a continuous elongated discharge path extending in two directions from said .stem portion, and a discharge preventing 2. A discharge tube including a ring-' shaped portion, a stem portion opening into said ring-shaped portion, a stem within said stem portion, a pair of electrodes erected on said stem so as to project into said ring shaped portion, and a discharge preventing shield erected on said stem between said electrodes and their supports, whereb discharges ed to the long path around the ring-shaped portion of said tube.

3r A discharge tube including a tubular I portion closed upon itself, a stem portion opening therein, a stem within said portion, a pair of electrodes erected on said stem so as toproject into saidtubular portion, and a discharge preventing shield for ionic isolation of said electrodes except by way of the long path around said tubular portion.

4.. A discharge tube including a tubular portion closed upon itself, astem portion opening into said tubular portion, a pair of electrodes projecting from said stem portion into said tubular portion, and a discharge preventing shield tor ionic isolation of said stem portion, a base and circuit connecting portion aflixed to said stem portion, and current controlling elements within said base in extension of said connections to said electrodes.

6. The combination of a discharge tube including a tubular portion closed upon-itself, a stem portion opening into said tubular portion, a pluralityof electrodes extending into said tubular portion'from said stem portion, connections to said electrodes leading externally of said tube by way of said stem portion, a base afiixed to said stem'portion, current controlling elements within said base in extension of said connections to said electrodes, and means aflixed to said base for connecting said current controlling elements to an electrical circuit outlet.

' i 7. The combination of a discharge tube including a plurality of electrodes, connections to said electrodes leading externally of said tube, a base aflixed to said tube and having a plurality of spaced walls, the outer of which carries heat radiating fins, current control- --ling elements in circuit with said electrodes by way of said external connections includ ing resistance arranged within the space between said double walls of said base, and means afiixed to said base for connecting said current controlling elements to an electrical circuit outlet.

8. A discharge tube including a tubular portion closed upon itself, a stem portion opening into said tubular portion, a pair of electrodes projecting from said stem portion into said tubular portion, a discharge preventing shield between said electrodes, and a potential determining connection to said shield leading externally of said tube.

' 9. In a glow discharge device, a transparent envelope consisting of a transparent tubular member of relatively small crosssection, said tubular member being bent and the ends thereof sealed to each other, a stem portion opening into said tubular member, a

stem within said portion, a pair of electrodes erected on said stem and extending within said tubular member and an electrostatic shield mounted on saidstem and substantiallv preventing any straight line discharge between the electrodes. I

10. In a discharge tube, a stem, a pair of electron emitting electrodes supported there- 'by, a conductive shield interposed between discharge tube said .electrodes,an envelope enclosing said said electrodes and forming with said-shield an. elongated main discharge path between said electrodes away from said shield, and

an impedance electrically connected to said electrodes, said shield being electrically connected to the midpoint of said impedance.

12. In a discharge tube, a stem, a pair of electron emitting electrodes supported thereby, a conductive shield interposed between said electrodes, an envelope in tubularform, the en-ds'of which respectively surround said electrodes and said shield and form an elongated main discharge path between said electrodes and away from said shield, and an impedance electrically connected to said electrodes, said shield being electrically connected tozthe midpoint of said impedance.

13. In a discharge system, a stem, a pair of electron emitting electrodes supported thereby, a conductive shield interposed between the electrodes, an envelope enclosing said electrodes and forming with said shield an elongated main discharge path between said electrodes and away from said shield,

and means comprising conductive connections between said shield and said electrodes for controlling the potential of the shield relatlve to the more negative electrode dur-' mg each half cycle of alternating potential applied between said electrodes.

'14. 'In a discharge system, a stem, a pair of electron emitting electrodes supported thereby, a conductive shield interposed between the electrodes, an envelope enclosing said electrodes and forming with said shield an elongated'main discharge path between said electrodes and away from said shield, and means comprisin conductive connections .between said shie d and said electrodes for controlling the rise of potential between the more negative of said electrodes and said shield to insure early starting of the discharge between said electrodes during each half cycle of alternating potential applied thereto.

15. A discharge system comprising a pair of heatable electron emissive electrodes each adapted to be alternately cathode and anode, a conductive shield obstructing the direct path between said electrodes, an envelope enclosing said shield and electrodes and providing an unobstructed discharge path between said electrodes of greater length than the direct path therebetweeman ionizable atmosphere in said envelope, and means comprisin conductive connections between said shleld and said electrodes for controlling the potential of the shield relative to the more negative electrode.

16.- In a discharge system, a. stem, a pair of electron emitting electrodes supported thereby, a conductive shield interposed between the electrodes, an envelope enclosin said electrodes and forming with said shiel' an elongated main dischar e path between said electrodes and away rom said shield, and means comprising conductive connections including a current limiting impedance between said shield and said electrodes for controlling the rise of potential between the more negative of said electrodes and said shield to insure early starting of the discharge between said electrodes during each half cycle of alternating potential applied thereto.

Signed at New York, county and State of New York, this 12th day of-June, 1931.

v CARL J. R.'H. von WEDEL.

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