US2488169A - Neon-type sign - Google Patents

Description

Nav. 15, 1949 Wv J, BROWNER 2,488,169

NEON-TYPE S IGN Filed Feb. 20, 1946 2512 y y www Nov. l5, 1949 w. J. BROWNER 2,488,169

- NEON-TYPE SIGN l Filed Feb. 20, 1946 4 Sheets-Sheet 2 @E L. j2me/Z402? l n ///Zf/Z cfUz//fvzef l I J Nov. 15, 1949 l Filed Feb. 20, 1946 w. J. BRowNER' NEON-'TYPE SIGN I 4 Sheets-Sheet 5 jz/ 122 L/ DUHOUV [F100 106 l' Y!! Patented Nov. 15, 1949 :NEON-TYPE SIGN William J. lrowrnr,v Chicago, Ill., assignor, by mesne assignments, to Benjamin B. Schneider -andf'Max Dressler, both of Chicago, Ill.

1Application February 20, 1946, Serial. No. 648,967

8 Claims. 1 This invention .relates .to an electrical. .apparatus and particularly to sign utilizing a luminescent medium such asa luminescent Agas or vapor or mixture thereof, .generally referred .to in the trade as neon signs.

In accordance with the inventiomthere is provided a plurality of pre-fabricated letters .or indicia, each one ofwhich consists vof. glass or similar sealed tubing kcontaining the usual neon sign llingof gas and/ or vapor vor. mixture thereof. Each signelernent or indicia is free of any lead-in electrodes. The glass `sign `elements are preferably provided with suitable. Ymeans for temporarily or permanently anchoring the same to a sign support. This support may consist of any desired. mechanicalstructure strong enough to support the weight of thesignelements. The supportincludes as. a part thereof a. high frequency tank circuit in thefformof a plurality of conductors. The high frequency tank circuitcooperates with the sign elements to induce agaseous discharge within said lsign elementsin` a manner well known in thegaseous conduction art.

The use of a high frequency vacuum tube type of oscillator for energizing the sign elements provides a construction which has a peculiar `advantage as far as blinking a sign is concerned. In conventional neon signv installations, thermostatic switches or motor--drivenv interruptersare necessary to flash the signon and olf atregular intervals. With a high frequency oscillator, .it

is possible to incorporate, within .the circuit, simple control means whereby the oscillator blocks periodically. Thus, the effect on the'sign is to switch the same on and on at regular intervals.

A structure embodying'the invention is preferably so designed that the frame work ofthe sign, this being the stationaryV portion thereof upon which letters or indicia arev supported, consists of-conducting material such as iron, steel, aluminum, copper and like conducting materials in perforate `or imperforatefsheet form. These conductors function as electrical l conductors for high frequency currents. In accordance with thelpresent 'invention the ferromagnetic conducting `materials are preferred.- It is preferred to design the frame so that ample surface `for conducting the highfrequency-currents isfprovided. Thus, the ohmic resistance ofthe frame to the highfrequency currents mayl be-reduced to a negligible value. f

In' the practice of the invention, opposed conducting sheet metal electrodes generally in-one through such sign elements. l

plane have cooperatingV edges to define, an -insulating gap. Cooperating with such-electrodes are sign elements sogdisposed as tov lie in intense electric elds. It follows that everysign element must be disposed so as to extend acrossthegap. Due tothe skin effect at high frequencies,the eld pattern may generally extend to the outer edges of the electrodes. -So long as asign -element is disposed in proximity vto the opposing electrode surfaces Yand lies within the projected outline of the electrodes, it will be subjected to electric elds.

I have discovered that, if the-gap in lair `between opposing edges -of sheet metal conducting electrodes has a transversedimension of less than about three-fourths of an inch, for frequencies below about one hundred mega-cycles, `for example, `remarkable operating efliciencyandnfreedom from radiationresult. .The minimumgap separation .in air may be of the order ofone sixty-fourth of. an inch, :although this minimum distance will vary withinfairly wide=-limitsf-de .pending upon. such conditions as .break-.downpotential .of the atmosphere. atmospheric. v:windt tions, the dirt andrsootcontent .0f the.:.a.1Iz-m0s chere, the vtransverse electrode..dimensmnswperatingfrequency and the like. The-maximum gap dimension inair is-of the orderl of.i`fh..r,ee fourths inch. The preferred gap'dimenysicn is from one sixty-fourth to-three-eighihE inch. ,It is to be understoodV that theterm transverse dimansion indicates a dindensch normaljtothe electrode edges at a particular gap region .under consideration. As will be Iapparent later, the transverse. dimension of the electrodes, is not necessarily coincident with, the geometrical width thereof.

It isY understood that any ldielectric medium may be used as the seat of the electric Ifieldsi incident toi the flow of currents 'along the surfaces of the sheet'electrodes. In accordance with wellknown theory, the potentialgradients established in such dielectric materials is a `function of the dielectric constant. It, therefore, becomes apparent that, where other materials than air are used as a dielectric medium, the critical electrode spacing will have to be correspondinglyadjusted. In general, however, unless materials having high dielectricconstants are used,'-the gap dimensions vprevioi-lslygiven may be utilized.

i The signy elements themselves-'must bedisposed in sufliciently close proximity to the sheet electrodes so that an intense-electric .eld will pass inasmuch asfthe electric field intensity. drops-off inversely 'as-the Vgaseous conduction shall occur` having a radio frequency output of around two.-

watts is ampie for energizing a neon sign of the size previously given. Such an oscillator, when operating at a radio frequency of less than thirty mega-cycles will have negligible eld intensity at a distance of 300 feet, as presently required by' governmental regulation.

The simplest embodiment of the invention utilizes a disposition of sheet metal electrodes in one general fiat plane. However, the electrodes may be curved out of a fiat plane or may be disposed in parallel planes. The sole limitation is that the electrodes should have no common projected surfaces along their faces. Thus, sign elements may be disposed across the gaps and over-lie the electrode area rather than lie in the gap between electrodes or lie across the gap and beyond the outer edges of the electrodes. The sign elements in a simple form may generally lie in flat planes. However, it is possible to curve them, such curvature being normal to the line of sight. n

The sign elements themselves may be fastened to the sign structure, either temporarily or permanently, in any desired manner. Conventional fastening means as by flexible or rigid clamps or tierods may be relied upon. However, asimple means for maintaining the sign elements in position makes use of permanent magnets. Thus, the sign elements may carry small blocks of material such as Alnico, each of which is magnetized yand cooperates with ferromagnetic sheet metal electrodes. relative locations of the permanent magnets and It is, of course, possible to reverse the ferromagnetic material or use permanent magnets on both the sign elements and frame.

In order to fully utilize the flexible characteristics of the sign with regard to change in indicia, it is possible to utilize simple indicia elements,

Y some of which are straight and some of which are curved, and combine these to form complete letters. It is, thus, possible to build a sign of any desired size and showing any desired matter from a number of simple elements.

Each sealed element must have a substantial portion thereof disposed in the radio frequency field between opposed electrodes in order that To this end, it is preferred to shape the gap forming opposing electrode edges so that every sign element will have at least one portion thereof extending from one electrode across the gap to the other electrode. For ordinary purposes, a zig-zag arrangement suitably proportioned with respect to the height and Width of proposed letters and sheet metal electrodes may be provided. Other tortuous or non-linear shapes for opposed electrode :surfaces may be devised, depending upon the type of letters or the shape of sign indicia.

For a more thorough understanding of the invention, reference Will now be made to the drawings showing exemplary embodiments of the invention. It is understood, however, that various changes in the structure and lay out may be made to suit varying conditions and requirements.

Figure 1 shows a perspective view of a sign with a portion broken away and illustrating one form of the invention.

Figure 1aI is a sectional detail on line Ia-Ia of Figure 1.

Figure 2 is a diagrammatic View of a modified form of sign and showing an oscillator circuit. Figure 3 is an elevation view of a sign and diagrammatic View of an oscillator circuit illustrating a preferred modication.

Figure 4 is a sectional end view on line 4-4 of Figure 3.

Figure is a perspective sectional view of a sign and a diagrammatic showing of an oscillator circuit of a still further modification.

Figure 6 is a top view of the sign of Figure 5 but showing the sign in complete form,

Figure 7 is a perspective detail of one end of Ythe sign of Figure 5 showing electrode adjusting means.

Figure 8 is an elevation with certain parts broken away and in section illustrating a further modification of the invention.

Figure 9 is a sectional detail on line 9-9 of Figure 8.

Referring rst to Figure 1, the sign proper comprises flat members II) and II, preferably of sheet metal such as iron or steel. These members may have any desired length and are shown as being of rectangular shape for simplicity. Flat members I0 and II have opposing edges I2 and I3 separated by an insulating gap I4. Gap I4 may consist either of air or of any suitable solid insulating material. Sheet members I0 and II have curled or enlarged edges I6 and I'I, these being formed in any suitable manner such as by rolling. Edges I6 and I'I are adapted to ride in suitable grooves I8 in support members I9 and 2l). Support members I9 and 20 may be either of insulating or conducting material.

Support members I9 and 20 may be rigidly maintained in spaced relationship at one end by support wall 22. This support wall is here shown as forming part of a box 23, although this is unnecessary to the invention. Support members I9 and 2li at the free end are maintained rigidly in predetermined relation by hinged end member 24. Wall 22 and end member 24 are suitably insulated from members I9 and 20 or may be formed of insulating material such as Wood, glass or the like.

End member 24 is hinged for a purpose which will be apparent later. Support members I9 and 20 are so shaped as to provide troughs 25 and 26. Disposed over fiat members IIJ and II is sheet 28 of any insulating material. Thus, a thin sheet of rubber, wood or any other insulating material may be disposed in troughs 25 and 26. Sheet 23 may be omitted. Thus, sheet steel members I and I I may be utilized without any covering, or the surfaces of these flat members may be insulated by Varnish or paint. However, in many instances, it may be desirable to provide a suitable background for the sign letters, which background may be formed as an insulating sheet.

Pre-formed and pre-fabricated sign letters 3E) may be disposed between support members I9 and 20. In the simple construction shown in Figure 1, these sign elements are maintained in Y position by being so dimensioned as to extend into troughs 25 and 26. It is understood that 2, 488541 est Itj will be noted-.that each'ofther signielementsv 30 extends across ...insulating '.gap Ill.nu As has been. pointed out before, insulating gapil Visn smallasfar as transverse dimensions are concernedlandgin air, Would.be..between about one sixty-fourth .i and`vv three-.quarters i inch. Thev transverse gap.v dimension.. does notjnecessarily have toremainuniform along thegap lengthy.

Box 23 may contain any suitable sourceV of radio frequency potentials such as` asimpleoscil.-V lator.. Sheet metalmembersloand Il are con,-

necteds to theoscillator:soA that a. difference of radiorequency:potential.- may tbe imposed across insulating-.gap J4.

With. suitable .frequency and power,y the letters will have Va vdischarge A`induced ,therein to render thegas and/orfvapor.- luminescent.

Referring: nowfto .'Figure; 2,1electrodes-,135 and 36;;are. shown.` These electrodes are.` sho-wn in diagrammaticiorm and :.norattempt toshow proportions .r or. .dimensionszhasobeen amado.. s., Thus, electrodei=35...hasi.a .branoh;35 .;extending `on the other sideloielectrodes3l=,so.that electrode :3S is disposed betweentwogarmssofnone electrode.. ElectrodesiSland 36 are-rconnectedtto terminals 31 and .38' -ofan ginductance: BillV l Inductance .39.Y

hasintermediate pointconnected by lead 4IY towinding i12-fof--translormeivt3.:v Point` 40 .may

be-varied-to insure-propermatching ofv ther sign elements loadvto Ythe oscillator-. Transformer..

has-primaryylltl:'energizedfby any; suitable source f of-alternating lpotential.-l Transformer i3 --has lament winding-d5`v connected byleads`4 ll-A and i? to'larnentary cathode dfoffvacuum tube49fl Tube 49 `has control-grid'^50 connected"throughsuitable grid` resistorwtll*backftoA the cathode.v` Control .grid `50'is also connected through *block-i` ingcondenser 52 to' terminal 3T`of inductance 39:L

Vacuum tube 49hasanode53 connected; by lead 54to terminal 38T y Transformer windings li2-andV 45 have-a 4com mon. connection to' leadLllT' Itis understood that winding :32"fu`rnishes sui'cient potential' toenergizethe anode circuit of tube'49- The-circuitshownin Figure 2 isone form of' a -simpleoscillator which maybe. used to' energir/ie` electrodes .35 and 36... Otherforms of osci1" latorsV may be use.d,.it being understood that vthe frequency is adjusted. to .have a value. desirable' for; sign operation. Sign elements 56 `may be disposed-across .the electrode structure. In. the form shown inFigure 2, each sign element liesv across two insulating gaps. Thus, one gap 5Tis` formed between4 electrode. 35 .and electrode 36. Theother gap 58 is formedbetween electrode.` 3S andelectrode. In actual practice, electrodes 35.; .135aand .36 will have a substantial area with gaps 5l and 58 being small, of the dimensions set -forth above, 'incomparison- -to sucharea. It is aclear thatthe sign .construction shown in Figure .l may loe-modified inview ofFigure 2 to pro- *A vide '.ftwo: gaps. instead; ggf; the single., one. Also, a sin-gleletter. may-.extend .across onegap only.; Referring;novvr:to'iFiguregS,n a lmodified signstructure -shovvnifwhereincacnY irregular. shaped insulating. hgap .is f. utilizedfr. By. proper;.; shaping.;l of. the1gap,i itziszpossibleto devise such a gap. asVV will-'ipermit :of: 'satisfactoryidispositiomofvrvarious; sign elementsover theelectrodesina mannerso 6 "S that each -sign'element-:crosses -thagapwI Thus, specificallyreferring- --to .Figurev 3,'-sheetf metal electrodes--60'and VV6i-- are provideda# Electrodess ti! 'and 6| Ahave opposing- -gap defining :edges 22* vand t3. These edges define gap 64 -havingthe1-fy outline shown'as one example.V Thus,\as shoW-n,- gap iid 'has a straight portion -655 followed by-a pluralityv of substantially' `V-shaped portions 66 andy terminating` in straight portion V61;.

1 tion. 65 need not .necessarily be 'straight' or form a V." If"desired,"these portions .may be irregue.` lar or may denne a regular cyclic curve, such as"v` a sine wave, for example. It is to be understood that electrodese and .8l are endowed with suffi'-v vcient strength so that-portions .denin'g the gaps will .be satisfactorily supported.

Meansv may beiprovided for adjusting the transverse gap dimension. A simple-means, shown in, detail in Figure 4, consists of bossesg'l and-'Il l Ycarried by electrodes 60 and SII The spacingbe.-

tween bosses may be controlled by bolt l2. Bolt- 12 threadedly engagesboss 'H and is. loose rin.. boss Nl. Rubber pad 73. between the bosses is provided to maintain the separation Straight portions and'l of thev gapmay be provided at spaced intervalsalong the sign as a whole if the sign lengthis great and .if such. straight portions are desired. It is also-possible to provide bosses i@ and 'Il and adjusting `bolt 12 at intermediate places along theA sign`- length.

The surface of electrodes 60. and,6l. may; -.be covered with any suitable sheetinsulatingmaterial as previously disclosed It is preferredin.. this particular instance to have electrodesll and i 6L of. somejferromagnetic material such as sheet Y .".having any desired. gas or mixture of gases or vapors-at any desiredpressure. The sign. `ele.- rnentsare cemented or joined togetherto .form a .composite sign element, in .this instance letter4 H, although they need not be. The cementing. or joining of the sign elements into a letter or in'- dicia before attaching them tothe sign is preferred.

Additional sign elements may be formed, such. as 16, in the shape of P. Sign element 71, having the curved shape shown ,may cooperate with sign element ,'16 to change the P to B. It isevident that innumerable. combinations .of different shapes of sign elements may befutilized to formdiierent letters, numerals or sign indicia in.gen. eral.

The .length of -each sign element and the shape andoharacterlof the gap are so proportioned thaty every. sign element crosses the insulating gap at least. once.v The .outline ofthe entire insulating './gap is,'. obviously; subject to innumerable modifications, depending upon the size, character and. disposition .offthe vsign elements and thedesired composite elements.

Electrodes -lllandI ,lvfmay vbe energized in. any suitable lfashion. Thus,Y a diagrammatic oscil. lator;l circuit? is r vshown gener-ally similar y to the i circuit-.oFigure 2. Power-transformer yI3-,inv Figure; 2 .is modified toffprovidelan; autostransy former-ASI.. In addition, grid .resister -5 I .is vari able.

As is well known in the art of blocking oscillators, it is possible to provide sufficiently high grid resistance so as to prevent continuous oscillator operation. The oscillating system may then operate for a certain period of time and become blocked. During the blocking, the charge in blocking condenser 52 gradually dissipates and permits renewed oscillator operation. By controlling the time constant of condenser 52 and resistor it is possible to control the on and off time of the oscillator. A simple neon sign flasher may thus be provided.

The various sign elements may be retained on electrodes 60 and 6| in any desired fashion. It is possible to maintain the composite sign ele-l ments in position in Figure 3 by simple mechanical retention, as illustrated in Figure 1. However, a modified retaining means is provided and serves to endow the sign with substantial advantages. Each sign element or composite sign elements may have cemented thereto one or more blocks 18 of permanent magnet material. The Well-known family of alloys of which Alnico is an example may be used. Such blocks are cemented or otherwise permanently fastened to sign elements l5 or 16, as the case may be, and cooperate with ferromagnetic electrodes 60 and 6|. The force of attraction due to Alnico may be sufficiently great to maintain a sign element strongly in position without requiring excessively large blocks of metal. In general, it is preferred to dispose the permanent magnet blocks so that they will not lie across an air gap. However, the precise disposition of the magnetic blocks is of no importance and may be varied within wide limits. The lblocks may be disposed between a sign element and electrode surfaces as shown in Figure 4, or the blocks may extend laterally of a sign element as shown in Figure 5. in the latter case, the sign element may be closer to the electrode surfaces.

The means for adjusting the width of the air gap may be relied upon to control the character of the load imposed upon the oscillator. In this Way, the radio frequency potential and frequency may be controlled within substantial limits. With variation in the number of sign elements on the electrodes and thus a variation in load, it may be necessary to vary the gap to maintain a predetermined frequency.

Referring now to Figures 5 to 7, inclusive, a still further modication is shown. Elongated insulating blocks 30 and Sl may support an electrode structure as shown. Thus, insulating block 80 may have a U-shaped sheet iron electrode 82 enclosing a portion thereof. Similarly, block 8| may have U-shaped electrode 83 enclosing the same. Between electrodes 82 and 03, there may be disposed at least one, or more if desired, plain electrodes 84. It is understood that both sides of the sign are the same. As shown, insulating gaps 85 and 86 are provided between the various electrodes on opposite sides of the sign. Gaps 85 and 86 are shown as straight, for simplicity, but may assume the general shape of gap 64 illustrated in Figure 3, and are formed by projecting strips from insulating blocks 80 and 8|.

As shown in Figure '7, each insulating block has boss 88 cooperating with bracket 89 carried by one of the U-shaped electrodes. The boss and bracket have bolt 90 for adjusting the transverse dimension of the gap. As shown in Figure 7, bolt 90 may conveniently turn idly in bracket 89 but threadedly engages boss 88. By suitable construction of bolt 90, such as by under-cutting, it will be evident that the spacing between the boss element such as described in connection with Figure 3.

The oscillating system for energizing the sign comprises vacuum tube |00. This vacuum tube may be any one of a number of types of tubes.

As shown here, this vacuum tube has a plurality of sets of electrode assemblies such as a diode and tetrode. The system described herein is particularly adapted for universal operation on either alternating or direct current. For volt work, a type 117 tube may be used for moderate loads. Thus, tube |00 has heaters |0| and |02 in series across 110 volt lines |03 and |04. Cooperating with these heaters are Cathodes |05 and |06. Cathode |05 is connected through condenser |01 to line wire |03. Cooperating with cathode |05 is anode |00 connected to line wire |04.

Cathode H05 is connected by wire ||0 to line wire |03. Cathode |00 is also connected by grid resister to lead H2 going to control grid ||3 cooperating with cathode |06. Lead ||2 is connected through blocking condenser ||4 to terminal ||5 of inductance IIS. Inductance ||6 has intermediate point connected by lead I8 back to rectier cathode |05. Lead ||8 is also connected to accelerating electrodes ||9 of the tetrode. The tetrode has anode |20 connected by lead |2| to terminal |22 of inductance H6. The output of the system is taken at terminals ||5 and |22. Thus, terminal ||5 is connected by a lead to center electrode 84, while terminal |22 is connected by leads to end electrodes 82 and 83.

Upon application of direct current, assuming that line wire |04 is positive to line wire |03, it will be clear that the rectifier and tetrode Will be connected in series. The circuit goes from line wire |04 through the diode to lead I8 to tap thence through a portion of inductance ||6 to terminal |22. From |22, the direct current circuit continues to anode |20 through the tetrode to cathode |06 thence to line wire |03. At the same time, accelerating electrode ||9 will be raised to a suitably high potential. On alternating current, the diode will suppress negative portion of each cycle and permit the system to operate at those portions of the cycle when line wire |04 is positive to line wire |03.

As far as the generation of oscillations is concerned, the circuit shown is a conventional oscillator and a detailed description of the operation thereof may be found in any standard reference book.

Referring now to Figure 8, a, sign having substantial vertical dimensions is disclosed. This permits the use of a substantial series of vertically arranged letters or individual large letters. In this particular modification, electrodes |30 to |39 inclusive are provided. These electrodes may be of any suitable conducting material such as sheet iron, as previously indicated. As shown, electrodes |30 to |33 inclusive and |36 are of simple rectangular shape and provide a simple linear insulating gap between them. Electrodes.

.|34 .and y|3,5.,are Vshapedto Yprovide agap gen,- erally. similar to that shown.in Figure 3. Thus, .electrodes 13A. and l|1\5.pro vide vgap |38'. Gaps between adjacent electrodes may` be formed by exible. insulating ,material |401 Such material may consist of .rubber or, any. other elastic material. The.rubber mayextend throughout the full extent of the .gap or `merely at the .ends of the electrodes near the sidesthereof.

As `shown in Figure 8, electrodes|3|l to .|36 are disposed so that. they 4all `liein Aone general plane and, when vertically mounted, would appear as shown.- The electrodes are maintained in aligned relationship by suitablelsupporting means. Thus,

. simpleA U-shaped members |42 are provided at the opposite sides of the electrodes. U-shaped supporting means |42. may have insulating block |43 within whichtheelectrodeedges may move. A bottom supporting member |44 is provided upon which thestack of Velectrodesis supported. Any suitable clamping means, such as screw.|46, may be provided at oppositesides of the sign to adjust the transversedimensions of the various gaps. By disposing live rubber between adjacent electrodes, it is clear that any desired relationship between gaps may be maintained while adjusting the .dimensi ons thereof..v Thus, the gaps may be equal, or some gaps may be wider than others.

The entiresurfaceotthe electrodes may be covered by insulating sheet |48 of any suitable material. Suitable signi-elements' may thereupon .be disposed in various portions of the signysuch sign elements being-retained Ain-position either by the magnetic means disclosed in Figures 3 and 5, or by any suitable mechanical means.- Itis understood thatF the electrodes are so wired as to provide for a'potentiardifrerence-across any gap, such potential diierence beingsupplied by -any suitable oscillator.Y Inasmuch Yas the electrical connections forA the various electrodes will be obvious to anyone skilled in the art, no detailed showing needV be made;A It vis Vunderstood that electrodes lst-,132,- |34 `and |36 may either be connected in parallel-with the. remaining electrodes also connected in parallel and of opposing polarity or, in the alternative; electrodes vand |36 may be connected to the oscillator Witnthe intervening electrodes forming aseries cascaded arrangement.

It is understood that the insulating gaps in the various modications shown will have transverse dimensions of the order previously given, namely between about one sixty-fourth and three-fourths of an inch. In general, the transverse dimensions will be a function of the nature of the insulating material, such as air or solid material, the desired operating frequency, the physical dimensions of the sign elements, the amplitude of the radio frequency potentials, the extent and nature of the medium extending between the electrodes at the gaps on the one hand and the interior of the sign elements where ionization is to be effected on the other. It is well known that the dielectric constant has a profound effect upon the nature of the potential gradient existing between two electrodes. In a structure having a number of diTerent dielectric media, the dielectric constant of one medium will affect the potential gradients in the remaining dielectric media. It is, howeverpcomparatively simple to adjust the operating frequency of the oscillating system including the work circuit. Recourse may be had to tuning capacitors or conductors for suppleinenting or correcting any departures from predetermined circuit -constant occasioned by variastantial power output. Such considerations, however,.are well known in the electronic art and needn@ .extended discussion.

The amplitude of radio frequency potential for proper sign operation may be adjusted by increasing/ the same till proper illumination isefected Itisimpessibleto state denitely what particular amplitude `of radio frequency potential is necessary. The amplitude itself is dependent upon `the nature of the gas within which a discharge is; to occur, the frequency, the electrode shape, physical distances between electrode surface and sign elements, the reactance of the circuit companents, the quantity of residual ions in the sign velements and other obscure factors. The simplest and most practical procedure is to adjust the amplitude to a level giving desirable operating conditions. The adjustment of such amplitude is a matter well within the skill of any man in the electronic art and needs no description.

While the mechanical sign structures have been illustrated as at, it is evidentthat they maybe bentto lie in curved planes or irregular planes.

I claim:

L1A neon type sign comprising a support including at least two spaced electrodes defining a. gapA therebetween of between about 1/64. and about 3/af', each ofsaid electrodes having a projected outline having the dimension transverse tothe gap large in comparison to the gap dimension, said electrodes `being adapted to be energized by-high-frequency electric currents with Va-rado frequency difference of potential existing across said gap,l atleast one sealed transparent envelopecontaining anionizable medium atia reduced pressure, said envelope. being free of metallic electrodesand said medium being adapted tobefexcited to luminescence bysaid Ahigh-,frequency field, and means for maintaining said envelope substantially in Contact with said electrodes and extending across said gap, said envelope lying approximately within the projected outlines of the electrodes.

2. In combination, a vacuum tube oscillator, and neon type sign comprising a support including at least two spaced electrodes defining a gap therebetween of between about 1/64 and about each of said electrodes having a projected outline having the dimension transverse to the gap large in comparison to the gap dimension, means for feeding the output of said oscillator to said electrodes to generate a radio frequency difference of potential across said gap, at least one sealed transparent envelope containing an ionizable medium at a reduced pressure, said envelope being free of metallic electrodes and said medium adapted to be excited to luminescence by said high frequency eld, and means for maintaining said envelope in proximity to said electrodes across said gap, said envelope lying approximately lwithin the projected outline of the electrodes.

3. The neon sign according to claim 2 wherein said gap is tortuous.

4. The neon sign according to claim 2 wherein said vacuum tube oscillator is of the blocking type and is adapted to go on and off intermittently for blinking said sign.

5. A neon type sign comprising a support including a plurality of spaced electrodes defining a gap therebetween of between about 1/64" and about each of said electrodes having a projected outline having the dimension transverse to the gap large in comparison to the gap dimension, means for impressing a high frequency potential on said electrodes to provide a radio frequency difference of potential across each gap, at least one sealed transparent envelope containing an ionizable medium at reduced pressure, said evelope being free of metallic electrodes and said medium being adapted to be excited to luminescence by said high frequency field, said envelope being large enough to extend at least across one gap for substantial distances from said gap in a direction transverse to the gap, and means for maintaining said envelope in proximity to said electrodes and across said gap, said envelope 1ying aproximately within the projected outline of all of the electrodes.

6. The sign according to claim 5 wherein resilient means are provided for maintaining adjacent electrodes in position to dene said gaps and wherein means are provided for compressing said resilent means and adjusting the transverse dimension of all gaps simultaneously.

7. A neon type sign comprising a support including at least two spaced flat electrode surfaces, means for maintaining said surfaces so that they lie in one plane with the edge of one surface opposing an edge of the other surface to dene a gap therebetween of between about 1/64 and about '-/s", said electrode surfaces having dimensions transverse to the gap large in comparison to the gap dimension so that the electrode area is large in comparison to the gap area between edges, means for impressing electric currents on said electrode surfaces at a radio frequency to develop a radio frequency difference of potential across said g-ap, at least one sealed transparent envelope containing an ionizable medium at a reduced pressure, said envelope being free of metallic electrodes and generally lying in a nat plane, and means for maintaining said envelope against said electrode surfaces and across said gap, said envelope lying within the projected outline of the electrodes and gap surfaces and extending for substantial distances along said surfaces from said gap.

8. A neon type sign comprising a support including at least two spaced electrode surfaces, means for maintaining said surfaces so that an edge of one surface opposes an edge of the other surface to define a gap therebetween of between about 1/e4" and said electrode surfaces having dimensions transverse to the gap large in comparison to the gap dimension so that the electrode area is large in comparison to the gap area between edges, said electrode surfaces being adapted to be energized by high frequency electric currents with a radio frequency difference of potential existing across said gap, at least one sealed transparent envelope containing an ionizable medium at a reduced pressure, said envelope being free of metallic electrodes and said medium being adapted to be excited to luminescence by said high frequency field, and means for maintaining said envelope in proximity to said electrode surfaces and extending across said gap, said envelope lying approximately within the projected outline of the electrode and gap surfaces.

W'ILLIAM J. BROWNER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,832,672 Trouant Nov. 17, 1931 2,136,924 Reitherman Nov. 15, 1938 2,142,633` Dey et al. Jan. 3, 1939 2,166,036 Bertoye July 11, 1939 2,181,889 Hanson Dec. 5, 1939 2,184,530 Penney et al Dec. 26, 1939 2,185,674 Michel Jan. 2, 1940 2,332,008 Fodor June 15, 1943 FOREIGN PATENTS Number Country Date 490,415 Great Britain 1938 502,572 Great Britain 1939 507,906 Great Britain 1939

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