Historical Document · 1959
The Burroughs stacked-cathode indicator tube, filed 13 December 1955 and granted 17 February 1959: photo-etched character cathodes, offset stacking for wide viewing, insulating light-absorbing rear coatings.
Feb. 17, 1959 H. J. HAMPE 2,874,320 INDICATING DEVICE Filed Dec. 13, 1955 2 Sheets-Sheet l Essas IINIL INVENTOR. HEREERT J, HAMPE BY -6-6-1 2-1-2, 6au-see,9. ATTORNEY Feb. 17, 1959 H. J. HAMPEL 2,874,320 INDICATING DEVICE Filed Dec. 13, 1955 2. Sheets-Sheet 2 INVENTOR, HERBERT J. HAMPE BY 6-&aal 3, 6a-ee, , AT TORNEY United States Patent Office 2,874,326 Patented Feb. 17, 1959 2 Fig. 1. represents: a side elevation of a completed tube: Fig. 2 is a view of the prong or base-end of the tube; Fig. 3 is an enlarged exploded perspective view of a 2,874,320. number display tube embodying one form of the present INDICATING DEVICE. 5 invention; Herbert J. Hampel, Philadelphia, Pa., assignor to Burs Fig.Fig.1; 4. represents an enlarged section on line: 4-4 of roughs Corporation, Detroit, Michi, a corporation of Fig.5 represents a section on line 5-5 of Fig. 4, show Michigan ingone form of studmounting; Fig. 6 represents: a sectional detail of a modified form Application December 13, 1955, Serial No. 552,748. O of stud mounting; 16 Claims: - (C, 313-109.5) 1. Fig. 7 is a view of one of the cathodes and is illustra. tive of all of the cathodes, as ready for bendings and assembly; This invention, relates to indicating devices and meth- 15 Fig. 8, represents an enlarged sectional view on line 8-8 of Fig. 4. ods of making the same and more particularly to glow Fig. 9 is a fragmentary and exploded view of a cathode type gas tubes for showing any one of a plurality of num bers or other characters' as selected; as assembled; stamping, etching, or electrolytic action, are 'coated with: insulating material on those surfaces from which elec: more...clearly-show the arrangement of one cathode-charac which: substantially right angles to the plane of that cathode, pro Fig. 10 is a-front view of a framed assembly of one Neon gas glow tube devices displaying an array of nurs merical characters are known to the art, as exemplified, 20 particular. cathode character as produced by a stamping or etching process in accordance with this invention. by United States patents to ; H. P. Buswau and F. B. Fig.11 is an enlarged front view of one of the cathode Maynard, Nos. 2,142,106 and 2,756,366, respectively: However, these tubes have been subject to manufacture. characters from the frame of Fig.10; Fig. 12 is a pictorial representation of the process of ing difficulties and have: shown in many applications wide variation in firing and quenching; voltage: requir 25 spraying insulating material on the back of a framed as sembly of cathode characters; w ments, for the various characters. As a result, tubes Fig.13 shows an alternate-embodiment of the integral capable of displaying many characters are somewhat. costly for initial installation and requires complex and: structure-connecting a mounting tab to the frame on which extensive: circuitry, for: reliable: operation. A. further: the cathode-characters are supported when produced; and Figs. 14 and 15 pictorially illustrate the step of bending. handicap, is experienced in the electrode: mounting; and:positioning, arrangements used: which result in a consides the integrally connected lead of a cathode character to a erable depth for: the complete display, limiting; the: angle right angled position. As shown, in Figure -1, an embodiment of the invention in which a character can be viewed, causing an apparent in a transparent envelope 9, which has been variation in character as seen from separated points, and. 35. is-assembled evacuated and then filled to allow pressure with a gas such hiding or masking effects upon the rearmost characters neon, making the tube suitable- for glow operation. from...forward characters and from: reflections of: room; as: Envelopes 9 is sealed to a base 16, which may be a con lighting: from broad areas of supportings insulators: Mounting techniques which provide for: compact display. ventional base disc or button of glass through which a plurality of leads. 11 project to. connect the various elec assemblies have included insulating structures: which im pede; the current paths: necessary to uniform; glow over: 40 trodes of the glow. tube. into control and indicating cir cuits. Once: the tube. has been evacuated- and the gas for all portions of each character; glows operation has been introduced, the tube is sealed . An object of this invention is to provides an indicating tube suitable for wide-angle viewing and; with negligible'; off at vacuum seal 12, preferably located in base 10... so as to leave a transparent and unobstructed viewing face. 13 parallax effects for all characters.", Another object of this invention is to provide;a novel: 45 at the other end of the envelope.9. The assembly of cathodes 14, anode 15, and a support structural arrangement possessing: improved precision: and durability yet adapted-for-rapidland economical manus: ing structure of electrically insulating material comprising. facture. .. . a disc 23 and studs 22 and 24 are positioned within en Another object of this invention is to provide an indi..' velope 9 very close to the transparent end face 13. Leads cating tubehaving superior electrical characteristics.. . 50 25 provide electrical connections from the cathodes 14 to A further object of this invention is to provide an assemes individual base pins 11. A similar lead 28 electrically bly, of...characters wherein hiding of one character by ane. connects anode -15 to another base pin 11. Figure 2 other...is reduced to a minimum so each number is clearly: shows base-10 with vacuum seal 12 centrally positioned visible when illuminated, and all characters are in a close and with leads i positioned on a circle as is the practice ly stacked, but insulated relationship, with the assembly: 55 for "button-base' vacuum tubes. A slight bend in each lead 25 and 28 from the axis of its passage through disc in-close proximity to the viewing end of the tube, A still further object of this invention is, to provide:a:: 23 to reach one of the leads in the smaller diameter of method for producing the assembly: of respective charac the leads 11 may serve to hold disc 23 from movement ters for a character display, tube, whereby the respective: away from face:13, although special provision for hold characters together with their: supporting tabs and con 30 ing:the disc from: such movement may be provided. Figure 3 shows: the tube parts in an exploded view to necting leads are formed as individual conductors; by: ter.14 behind the other, in a single file, with the anode 5. tronic conduction is not desired, bent intoshape for final: behind the assembly of cathodes. The filamentary, na assembly, mounted upon a supporting structure of insulat-. 65 ture of the cathodes which, together with the relative pro ing material, and encased in: a partially evacuated tube: portions, and positions of their component parts, described which permits viewing, maintains the low-pressure: gas is below, results in substantially equal visibility for the dif atmosphere needed for. glow. discharge, and holds leads ferent-luminous numerals of the illustrated arrangement, for. connections from outside the tube...to...the-electrodes: is apparent, also, in this figure. within the tube. 70 Each cathode has a connecting lead 25 which is an inte Reference is made to the accompanying drawings, in gral part of that cathode and which, when folded back at 2,874,320 3 jects rearwardly through the assembly of cathodes and the disc 23 for connection to its particular lead-in pin. Each cathode is insulated from the other in any suitable fashion, and when the assembly is stacked compactly in 4. the largest and smallest characters are not noticeably dif ferent in size from a viewer's position. The diagonally sloping portions of "four" and "six" and the horizontal portions of “2,' '3' and '5" are illustrative of such laterally offset portions. Except for the tabs 16 and 17 which overlap anode 15, all portions of cathodes 0.10 inch in certain embodiments of the invention made 14 are of smaller dimensions and lie within the diameter to date. of anode 15. This distribution within an anode ring in As a means for obtaining this compact, relatively thin sures uniform glow intensity from various portions of all pattern assembly, each cathode 14 is stamped, etched or O cathodes. Tabs 16 and 17 have been shown of consider otherwise developed from a thin sheet of metal, pref able width, for clarity, but can be made of narrower width, erably copper, which may have a thickness of the order particularly along the portion not surrounding holes 19 of approximately 0.002 to 0.004 of an inch and at the and 20 but extending therefrom to the character which is same time each character is formed it is provided with supported by that tab. Furthermore, the front surfaces two spaced apart upper and lower tabs 16 and 17, pref s of tabs 16 and 17 for the foremost character also are erably in aligned relation for mounting on a stable Sup coated with insulating material 27, as indicated by the port, each of the tabs 16 having an aperture 19 and each stippling in Fig. 4, to prevent glow from this easily visible of the tabs 17 having an aperture 20. The tabs 16 and area. The remaining tabs behind the foremost pin may 17 are similarly located on each character electrode for also be coated with the insulating material if desired. alignment so that when assembled in the final stacked re 20 Figure illustrates in detail the mounting arrangement lation with the characters in the desired relative positions provided by the studs 22 and 24. Stud 22 is used as the there will be a row of tabs 16 with registering apertures example, and as previously described the stud forms an 19 and a row of tabs 17 with like registering apertures 20. integral portion of disc 23, and upon which anode 15 The row of tab apertures 19 receive a supporting stud 22 and the mounting tabs or stubs 16 of cathodes 14 are of insulating material projecting from the face of the sup 25 mounted. Each cathode 14 and tabs 16 and 17 is coated porting disc 23 and the row of tab apertures 20 receive a on its rear face with an insulating and preferably light ab supporting stud 24 of insulating material projecting from sorbing material 27 which isolates each electrode from the same face of the disc 23, such disc being of insulating adjacent electrodes and also prevents electronic current material such as ceramic or mica. from flowing from cathode areas from which glow is not The connecting leads 25 are formed as extensions of the 30 desired. Leads 25 are similarly coated to prevent glow various cathodes 14 and at points thereon which may be therefrom. With this control over the cathode areas different for each cathode, so that, in the illustrated ar which can support electronic current, current is limited rangement, they may be projected through separate holes to those areas from which glow is required and a high 26 in disc 23, when assembled, and do not contact one ratio of light output to current is obtained. Further, the another. Behind disc 23, the leads 25 connect to base 35 resulting low current minimizes harmful sublimation and prongs 11. As shown in Fig. 3, anode 15 is in the shape contamination effects and minimizes outgassing of tube of a ring. It is provided with diametrically spaced apart elements due to heating; providing long tube life without sacrificing light output. apertures 30 and 31 and has lead 28 attached to its rear face for projection through disc 23 to an individual lead Figure 6 shows an alternate embodiment of the support 11 in a manner similar to that described for leads 25. 40 ing structure for the assembly of cathodes 14 and anode Once the assembly is stacked in its final form, leads 25 15. In place of the studs 22-24, the alternate embodi and 28 are bent to go to their respective base prongs 11. ment employs metal rods. One of the rods is in Figure 6 These slight bends behind disc 23 confine disc 23, anode and identified as "36.” Glass or other insulating mate 15 and cathodes 14 in this compact arrangement. Leads rial 37 is coated on that portion of rod 36 which will fit 25 and 28 being very flexible in nature can readily be bent 45 into hole 19 of each tab 16 and hole 30 of anode 15. Disc in a minimum of space to carry out the foregoing method 23 is provided with an aperture therethrough at the point of assembly. where rod 36 is to be positioned. An eyelet or grommet Figure 4 shows this assembly in its final form, viewed 38 is mounted in this aperture, and disc 23 and eyelet 38 from the face end of the tube. The linear lengths and are slid onto rod 36 until eyelet 38 abuts against the in continuing arcuate portions of each cathode character are sulation coating 37. The shank of eyelet 38 then is spot welded or otherwise affixed to rod 36. It is understood preferably formed of slightly different dimensions so that the manner as shown in Fig. 1 the overall thickness of the assembly is quite small, being in the order of 0.08 to that a similar rod, coating, and eyelet are used in place these portions of the numbers or characters are laterally of stud 24. offset one from the other. In this manner, each number or character is made clearly visible from the viewing end 55 Anode 15 and the tabs 16 and 17 of the cathode char acters with their back surface insulation 27 are then slid of the tube, when illuminated, and is not perceptibly ob onto the front or pointed end of each rod 36 over the scured by cathodes in front of it. In the illustrated em covered with insulating material 37. A collar 39 bodiment of the invention, the character representing portion with an insulated flange 40 is then slid down each rod 36 "Zero" has the largest dimensions of all the characters, ex until abuts against the insulating coating 37 and upper tending to near the inside diameter of anode ring 15. The most itcathode tab, where it is affixed to the rod by spot characters representative of "three," "eight" and "nine" 60 welding or other method. The same assembly steps are are smaller than the "zero" so as to be separately visible performed simultaneously the other mounting rod and when it is illuminated and alternatively not to obscure for the other side of disc for 23, anode 15 and the cathode the other characters when any one of them is illuminated. Each rod 36 projects into the region of the This arrangement pattern is continued in the remaining 65 characters. prongs 11 and is rigidly fixed to a base prong such as by spot welding. characters. When portions thereof do cross, the intersec base tion is made at an angle as near right-angle as is practical considerable mechanical strength is provided in as is exemplified in the crossing of "nine" over "three" theSince assembly of cathodes 14 on studs 22 and 24, the disc and "eight.” When portions thereof must be essentially 23 and the associated eyelets may be omitted and replaced parallel, they are kept in different lateral positions. Be 70 by another insulated collar to collar 39 to support cause of the thinness of the stack of character electrodes, the assembly of cathodes 14similar and anode 15 upon the stud. a slight lateral displacement between portions of each As shown in Figure 7, the numeral "zero" typical of electrode permits unobscured viewing over a wide angle. the characters produced by stamping, etching,iselectrolytic Since the displacements can be small, the difference in action, other process for production of small cross-sec dimensions for the various characters can be small, i.e., 75 tioned, orprecisely contoured characters. The supporting 5. 2,874;320 6 tabs: 16, and 17 with mounting holes 19- and 20: respec Sulating material, such as: molten, glass oria, suspension time as the character and out of the same material and as shown. The surface, tension and adhesive, forces, ex tively, and the connecting lead 25 are formed at the same: thus are integrally connected to the material out of which the character is formed. After a character is produced as shown in Fig. 7, the: back is sprayed with insulating material. 27, and lead 25 of Alundum;in a suitable liquid-vehicle, onto the back side erted on the material after it is applied to the metal will hold the material 27 in the shape shown in Figure 8 until molten material cools and sets or a volatile vehicle has. evaporated, leaving a dense, strongly adhering coating. is bent rearwardly to right...angles to the plane of the char The cathode 14 with its connecting lead 25 and support acter. The characters: or numerals are then placed upon. ing tabs 16 and 17 is then cut free of frame 50. the assembly of disc 23 and anode 15, as shown in Figure: Because of the precision, and fine detail: which can be provided by the stamping, etching, or electrolytic actions 9. for the "zero' numeral's cathode: 14. As each cathode used, numerous, changes in the product are possible, with is placed on studs: 22 and 24 its lead 25 fits through a hole 26 in disc 23, for connection to a particular prong 11 in in the: scope of this invention. As shown in Figure, 13, the tube base 10. the support tab 16 can have a narrower section 52 be Although stamping, electrolytic action, or etching can 15 tween it and frame 50. This provides for easier, and more precise separation of the tab 16 from frame 50, be utilized to produce the cross section as shown by area 14 of Figure 8, the photo-etching process of the Buckbee since the edge of tab. 16 is clearly observable, on the Structure. Mears Company is preferred because of its precise con trol. The sides of this truncated section slope to produce Figure 14 shows a cathode: 14 with its connecting lead a wider surface on one side than on the other side. This 20: 25 in the process of being bent to its right angle position preparatory to being mounted in an assembly of cathodes, difference is attained by controlled etching from both sides, causing the etching to remove material from one While hand bending is shown in. Figure 15, it is fully side more extensively than from the other side. within the scope of this invention to use tweezers, jigs, In order to insulate each cathode 14 from adjacent or other tools which are useful in metal forming by bend cathodes, and the anode 15 in a stacked assembly, the 25 ing. Once connecting lead 25 is bent into position, its back of each character may be sprayed or otherwise full length on both sides is coated with glass, Alundum, coated with an insulating and preferably opaque and or other insulating material, except for where it. will be. non-light transmitting and non-reflective material 27. bonded to a base prong 11 of the tube. This coating This coating 27 is as shown in Figure 8, of convex cross prevents unwanted glow and minimizes current, in the section with a major thickness of about 0.06 inch. Thus, 30 same manner as does the back coating 27 on the cathode 14. . . . the cross section of all cathode members comprises: a forward-looking electrode 14, with sides slanting to a From the foregoing is will be seen that each cathode. 14 is a separate character, with a backing 27 of insulating wider rear surface on which insulating material 27, is and preferably opaque, non-reflecting material. When coated. By making the rear side, which is coated, wider than the front side, a larger insulation barrier is inter assembled into a sequence of numerals, each cathode is: posed between successive stacked cathodes when they are Supported by tabs from insulated studs. projecting from assembled. . an insulating base. As so assembled, these cathodes. Figure 10 shows a quantity of one type cathode as form a compact. stack of numerals. wherein the outline integral parts of a frame, 50. Each cathode 14 therein 40 of each number is out of register with all other numerals. is produced complete with its integral connection lead Also, the opaque, non-reflecting backing eliminates dis 25 and support tabs 16 and 17. When the quantity of turbing reflections and limits glow to those front surfaces a particular cathode which is desired is less than the from which light is desired. This current limitation pro capacity of frame 50, then several different cathodes can vides a high ratio of light output-to-current. be produced in a given frame. The novel construction further provides for uniform, As stated in describing Fig. 8, the photo-chemical etch predictable and stable ionization and sustaining voltage ing process of Buckbee-Mears Company of St. Paul 1, levels. When a designer can depend upon ionization oc Minnesota, is preferred. This process is described in curring at Some definite voltage, he can provide much of United States Patents 2,536,383; 2,710,591; 2,710,814; that voltage as a pre-bias to which only a small voltage and 2,720,146 to N. B. Mears or N. B. Mears et al. In increment or pulse must be applied in order to fire the this process, a thin sheet of metal. is covered on both.sides 50 tube. Since transistor and magnetic core circuitry in with photo-sensitive glue, exposed on, both sides to a light. herently provide pulse outputs, direct interconnections pattern exhibiting a picture of the desired configuration can be made between such circuits and this tube, when of the final etching, washed to remove the glue from un pre-bias is used. This can save a large percentage of the: exposed areas, baring the metal in these areas, and etched. total circuitry of a display or indicating unit. by application of appropriate salt solutions to remove the, 5 5 The unique method of fabrication by etching results metal from these exposed areas. The result is a precise in dimensional precision of the parts which is not possible metallic-reproduction of the light pattern applied to the with standard die techniques. Further, the provision of integral mount tabs and connecting leads reduces assem metal sheet, wherein detail is; as fine and precise as the pattern a camera can photograph and which can be re 60 bly steps to a minimum, and the use of precision, parts in an assembly, achieves minimum screening or interaction produced in the light pattern which is applied to the metal since relative positions are closely controlled and small sheet, can be used. When single cathodes are to be produced, as shown in dimensions What is claimed is: Figure. 11, then the frame 50 encloses only that single 1. An indicating tube of the glow lamp type compris cathode 14 together with its connecting lead 25 and sup a gas-filled envelope having a portion thereof con port tabs 16 and 17. The quantity of cathodes per frame, 65 ing stituting a transparent viewing face, a plurality of planar the different cathodes which any particular frameen cathodes within said envelope having the active portions closes, and the dimensions of various tabs and leads are: thereof respectively formed in accordance with outline determined by the particular production requirements: representations of different characters, a coating of in Once the frame 50 and its cathodes 14 are produced, the 70 sulating material on one side of each of said cathodes, a planar anode within said envelope for ionizing the gas. in Figure 12. In the spraying operation, the wider back in response to a suitable potential difference between said, back side is sprayed with insulating material 27 as shown side of each cathode provides a shadowing effect and sub stantially prevents insulating material from falling on the anode and a selected one of said cathodes, structural means within said envelope mounting said cathodes and narrower front Surface.--Spray- nozzle: 51 projects in-75 said anode in stacked relationship with said coatings of 2,874,820. 8 insulating material on the sides of said cathodes remote 9. The process of making an electrode assembly for a from said viewing face, said structural means including gaseous glow type indicator tube having electrode mount integrally formed mounting tabs for each cathode ex ing structure which comprises coating a metal sheet with tending without the area of the character-formed portion photo-sensitive material which has the property of de thereof and also including mounting studs projecting 5. creased solubility after exposure to high-energy electro through holes in said mounting tabs and in said anode and magnetic radiation, irradiating said coated sheet with ra further including support means holding said mounting diation in a pattern which conforms to the desired struc studs and said cathodes and said anode in assembly there ture of electrodes, mounting tabs, connecting leads, and 7 with close to said viewing face of the envelope, said cath supporting frame, dissolving the non-irradiated coating material, etching to remove the bared metal where coating material has been removed, removing the coating mate rial of decreased solubility, spraying the resulting metallic structure with insulating material where electrical insula obstructing effect on character-formed portions of the tion and glow inhibition are desired, cutting the electrodes luminous cathodes more remote therefrom, and electrical complete with connecting leads and mounting tabs from conducting means connecting said cathodes and said the supporting frame, bending the connecting lead of each anode with the exterior of said envelope. electrode to fit into the electrode assembly, stacking the 2. An indicating tube of the gaseous glow type having electrodes in a close but insulated assembly, and affixing an assembly of character indicating electrodes compris said electrode assembly to the mounting structure and ing, in combination, a plurality of cathodes respectively connecting pins of the indicator tube. 10. In the manufacture of electrodes for gaseous glow produced in the shape of different characters, a connect type indicator tubes, the steps which comprise removing ing lead for each cathode formed of the same material metal from a metallic sheet by photo-chemical etching in as the cathode and integrally joined thereto, at least two a pattern which excludes from etching the pattern forming supporting tabs for each cathode formed of the same the desired structure of electrode, mounting tabs, connect material as the cathode and integrally joined thereto, and supporting studs for holding said cathodes in a closely ing lead, and supporting frame, and spraying this desired structure with insulating material where electrical insula stacked but insulated relationship, said studs engaging the supporting tabs of the cathodes and said engagement tion and glow inhibition are desired. 11. In the manufacture of electrodes for indicator being the sole support for the cathodes. 3. An indicating tube of the glow lamp type compris. tubes, the steps which comprise removing metal from both surfaces of a metallic sheet by controlled photo-chemical ing a gas filled transparent envelope, a plurality of cath ode electrodes and an anode in said envelope, each of etching, which excludes from surface etching the pattern forming the structure of electrode, mounting tabs, and said cathodes having a face of conducting material deline connecting leads within a supporting frame, maintaining ated in the shape of a different character to be indicated and a back surface of insulating material conforming to the etching action on a first face more extensively than on the opposed face thereby producing a smaller-area surface the shape of the character, and means mounting said cath on said first face than on said opposed face of the pattern odes and said anode in stacked relation in the envelope. excluded from surface etching and resulting in a trun 4. The tube defined in claim 3 wherein some of said cated cross section for members of said pattern, and cathode electrodes have a different width than others and Some are offset laterally from others, so that when the 40 spraying insulating material upon the pattern of remain ing metal on its surface of greater-area to utilize the cathodes are viewed through the viewing window, none of the cathode electrodes is obscured by any of the others. shadowing effect of this greater-area surface upon the 5. The tube defined in claim 3 wherein each cathode smaller-area surface so as to keep insulating material off electrode has at least two mounting tabs and a connecting of said smaller-area surface, and additionally spraying in lead integral therewith. sulating material upon those portions of the smaller-area surface from which glow is to be inhibited. 6. The tube defined in claim 3 wherein each of said 12. In the manufacture of electrodes, the steps which cathode electrodes has a plurality of mounting tabs and comprise removing metal from a metallic sheet by photo an electrode lead integral therewith, the lead extending substantially perpendicularly to the plane of the cathode chemical etching in a pattern which excludes from etching electrode itself. the pattern forming the desired composite structure of electrode and an integrally joined connecting lead, apply 7. The tube defined in claim 3 wherein the edges of the cathode electrodes are tapered so that the rear surface ing insulating material to portions of this electrode struc ture where electrical insulation is desired, and bending the which is coated with insulating material has a larger width connecting lead at approximately its juncture to the elec than the uncoated front surface, the coating of insulating material on the rear surface of the cathodes having a 55 trode so that the lead extends at a substantial angle to the plane of the electrode. generally convex surface. 13. In the manufacture of electrodes, the steps which 8. An indicating tube of the glow lamp type compris include etching a metallic sheet to form a filamentary ing a gas-filled transparent envelope, a plurality of cath cathode configurated into the shape of a character and odes formed respectively in the shape of different charac an integrally joined connecting lead and at least ters, at least two spaced means outside of the field of said 60 having one integrally joined laterally projecting supporting tab, characters and supporting all of said cathodes in mutually bending the connection lead at approximately its juncture insulated stacked relation axially of the tube without in to the cathode character so that the lead extends at a sub tervening material therebetween in the fields of said char acters for forming a pattern of said characters selectively stantial angle to the plane of the character, and utilizing visible through ionization of the gas about the cathodes, 65 the integrally connected tab to support the cathode char acter in proper position in a tube device. said cathode characters being dimensioned and offset 14. A glow discharge device for the selective display from each other so that they have a minimum obscuring effect on each other and projections thereof on a plane of a variety of luminous indicia in a substantially com normal to the axis of the tube are substantially non-co mon field comprising an envelope having a transparent incident except as to intersections thereof, an anode op to portion for viewing said indicia and containing gas at a low pressure suitable for glow operation, a plurality of eratively associated with said cathodes to ionize the gas thereabout in response to an ionizing difference of poten planar cathodes arranged in said envelope in closely tial applied between said anode and any of said cathodes, spaced electrically insulatively stacked relationship with and lead means for making individual connections to said out intervening light obstructing or reflecting material, odes when luminously active providing a viewable pattern of characters having dimensions and an arrangement of the parts such that the character-formed portions of the cathodes nearer to said transparent face have a minimum anode and cathodes externally of said envelope. 0. 75. each cathode comprising a metallic filament portion in the 2,874320 10 form of one of the indicia and being designed to have a sulating material between each cathode to insulate them low obscuring effect on the filament portions of other from each other, a separate anode electrode within said cathodes in the stack more remote from said transparent envelope for ionizing the gas in response to a suitable portion of the envelope, each cathode having a pair of potential difference between said anode and a selected one thin metallic mounting tabs integral with its filament por of said cathodes, structural means within said envelope tion and extending laterally in substantially opposite di mounting said cathodes and said anode in stacked relation rections away from the area generally defined thereby, a ship with said bodies of insulating material on the sides pair of spaced apart posts mounted in fixed relationship of said cathodes remote from said viewing face, said in said envelope but located outside of the area defined by structural means including integrally formed mounting the indicia formed portions of the cathodes, said posts en 10 tabs for each cathode extending outside of the area of the gaging said tabs and serving to mount said cathodes in character-representing portion thereof and also including said stacked relationship in the envelope, a plurality of mounting studs projecting through holes in said mount electrically conducting leads each having a portion thereof ing tabs in all of said cathodes and in said anode and entering said envelope and another portion thereof within further including support means holding said mounting said envelope in electrical connection with an individual 5 studs and said cathodes and said anode in assembly there one of said cathodes, said last portion of the leads being flexible and one or more of these portions assuming a bend in the envelope, said leads providing means for ap with close to said viewing face of the envelope, said cath odes when luminously active providing a viewable pattern of characters having dimensions and an arrangement of plying a sufficiently different electrical potential to any the parts such that the character-formed portions of the one of said cathodes relative to a reference potential exist 20 cathodes nearer to said transparent face have a minimum ing within the envelope to cause a luminous glow at the obstructing effection character-formed portions of the filament portion of the selected cathode. luminous cathodes more remote therefrom, and electrical 15. A glow discharge device as defined in claim 14 conducting means including a flexible wire portion con wherein each combination of a cathode and pair of necting said cathodes and said anode with the exterior of mounting tabs together with said lead extension thereof 25 said envelope. is constituted by a single thin metallic member in which said cathode and mounting tabs lie in the same plane and References Cited in the file of this patent said lead extension extends at an angle thereto. UNITED STATES PATENTS 16. An indicating tube of the glow lamp type com prising a gas-filled envelope having a portion thereof con 30 2,142,106 Boswau ---------------- Jan. 3, 1939 stituting a transparent viewing face, a plurality of planar 2,618,760 Hancock et al. ---------- Nov. 18, 1952 glow cathodes within said envelope having the active por 2,756,366 Maynard--------------- July 24, 1956 2,769,939. Williams --------------- Nov. 6, 1956 tions thereof respectively formed in accordance with out line representations of different characters, a body of in