US3242370A - Cathode glow indicator tube - Google Patents

Description

March 22, 196e Filed OCb. 5, 1962 R. A. MILLIKEN CATHODE GLOW INDICATOR TUBE FIGHE.'

3 Sheets-Sheet 1 March 22, 1966 R. A. MILLIKEN 3,242,370

CATHODE GLOW INDICATOR TUBE Filed Oct. 5, 1962 3 Sheets-Sheet 2 Mmh 22, 1966 Filed Oct. 5, 1962 l .lill

R. A. MILLIKEN CATHODE GLOW INDICATOR TUBE MII lhlllll 3 Sheets-Sheet .odes constituting another group).

United States Patent O 3,242,370 CATHODE GLOW INDICATOR TUBE Rankin A. Milliken, Hayward, Calif., assigner, by mesne assignments, to Friden, Inc., San Leandro, Calif., a corporation of Delaware Filed Oct. 3, 1962, Ser. No. 228,124 9 Claims. (Cl. S13-109.5)

This invention relates to gaseous indicator glow tubes.

More particularly, this invention relates to indicator glow tubes of the type particularly suited for use with circuits which utilize binary principles of operation. Tubes of this type may be designated as decoder-indicator tubes because they are capable, by reason of their electrode arrangement, of not only indicating numbers stored in electronic counters but of also functioning to interpret, or decode, the pattern of electrical signals appearing upon the output terminals of an electronic counter of the type in which said pattern of signals does not bear a simple one-to-one relationship, to the exciting terminals of said indicating glow cathodes, or at least contributing substantialy to this decoding function by way of reduction of apparatus external to the tube necessary for performance of this function.

Tube arrangements of this type may be seen in United States Patent No. 2,906,906, upon which the present invention is an improvement.

Up to the present time decoder-indicator tubes of this type have not proved completely satisfactory because of the complexity of their electrode configurations.

Accordingly, one object of the instant invention is to provide an improved cathode indicator glow tube having combined anode-shield electrodes each of which performs functions hitherto performed by separate electrodes.

Another object of the instant invention is to provide an improved cathode indicator glow tube particularly suited for use in conjunction with binary-type counting circuits, and for providing a direct visible readout therefrom.

A still further object of the present invention is to provide a structural arrangement comprising mutually cooperating cathodes, combined anode-shield electrodes, insulators, :and sputter shield electrode which obviates the necessity of threading many cathodes and insulators onto side rods, thereby making economically feasible miniaturized assemblies of la compaetness hitherto `attainable only at very great cost.

Briefly, the principles and objects of the instant invention may be embodied in a tube which comprises a gaslled envelope containing a plurality of indicator cathodes shaped in the form of desired, e.g., numerical, indicia and capable of manifesting their presence by sustaining a cathode glow thereabout. If, for example, this tube is to be used in a decade counter, it may contain indicator cathodes kin the form 'of lthe numerals 0 through 9. These indicator electrodes may be arranged in groups (e.g., all of the odd-number indicator cathodes constituting one group, and all of the even-number indicator cath- According to the invention a combined anode-shield electrode will be associated with the first group, and another electrically independent combined anode-shield electrode will be associated with the second group. Each combined anodeshield electrode Iserves the function of shielding its associated group of indicator cathodes from excitation by the other combined anode-shield electrode, or electrodes. In addition, each combined anode-Shield electrode serves the second function of providing an exciting field for provoking cathode glow upon any desired one, or more, of its associated indicator cathodes. This is in contrast to prior art devices wherein the spurious excitation shielding and exciting functions were served by distinct and ICC different electrodes for the same group of indicator cathodes. It will be apparent to those skilled in the art, then, that so combining these two functions in a single combined anode-shield electrode for each group of indicator cathodes makes possible the provision of a tube having all the capabilities and advantages of prior art devices, yet at the same time being characterized by a reduced number of the electrodes.

In addition to the indicator cathodes and combined anode-shield electrodes, the tube of this invention may be equipped with a sputter shield electrode which at least partially screens the tube wall and base connections fnom sublimed cathode material, which may be at least in part ionamin-ous, which may be at least partially conductive, or may, in some cases, be largely of insulating material and which may be equipped with an electrical exciting connection, though such a .shield may be .dispensed with in some cases, and should not be considered a critical part of the invention.

The sputter shield electrode may, in a preferred embodiment, also function mechanically to support the indicator cathodes and combined anode-shield electrodes in desired relation within the tube by engaging a stack cornprising said cathodes and anode-shield electrodes and supporting insulating means therefor. That is, the sputter shield electrode may not only embrace, or surround, the cathodes and combined anode-shield electrodes for sputter shielding purposes, but may also engage the associated groups of cathodes and anode-shield electrodes for the purpose of mechanical support. It is to be understood, however, ithat the advantages arising Ifrotm the provision of the combined anode-shield electrodes may be embodied in a more conventional tube structure (e.g., having side rods, or support posts, to mount the indicator cathodes as shown in United States Patent No. 3,042,826) without departing from the invention disclosed herein for minimizing the number of electrodes and base pins necessary in a device of the class described herein.

It will further be apparent to those skilled in the art that the number of contact pins, or base pins, necessary may be reduced to a minimum by providing a contact pin for each of the combined anode-shield electrodes and a contact pin for each pair of indicator cathodes which may be selected one from one group and one from the other group. The sputter shield electrode may also be eliminated altogether, formed of insulating material, left floatingf or excited from a tapped impedance connected across the combined anode-shield electrode leads as shown in FIG. 6. By this last arrangement the number of necessary base pins is reduced to seven in a tube capable of providing decoding in a binary coded decimal counter system. Other combinations of indicator cathode electrodes and combined anode-shield electrodes may be made as required by a particular circuit application. In addition, several sets each consisting of two or more groups of indicator cathodes, at least one combined anode-shield electrode being associated with each group, may be provided so that a simultaneous readout of a plurality of characters may be achieved from within a single envelope.

In operation of a decoder-indicator tube of the type of the instant invention, a single indicator cathode in a group may be caused to glow by the application of the proper exciting voltage between the selected indicator cathode and the combined anode-shield electrode associated with this indicator cathode. The combined anodeshield electrodes associated with the other groups of indicator electrodes within the common envelope will prevent interaction between the combined anode-shield electrode of the group including the selected indicator cathode and the indicator cathodes of the other groups,

thereby preventing spurious, or undesired, ow of an indicator cathode in a group other than the group including the selected indicator cathode.

The invention is described in greater detail by reference to the accompanying drawings wherein:

FIG. 1 is a perspective view of a tube embodying the instant invention;

FIG- 2 is a schematic representation of the tube of FIG. 1; l

FIG. 3 is an exploded pictorial view of a preferred indicator tube structure according to the instant invention;

FIG. 4 shows the mutually non-obturating relationship of typical indicator cathodes which may be used inV carrying out the instant invention;

FIG. 5-a shows a spacing insulator frame according to the instant invention;

FIGS. S-b and 5-c show positioning insulator frames according to the instant invention;

FIGS. S-d and S-e show the combined anode-shield electrodes of the instant invention; and

FIG. 6 is a schematic representation of an alternative embodiment of the instant invention wherein the sputter shield electrode is excited by a voltage divider located internally of the tube envelope and connected across the combined anode-shield electrode leads.

Referring to the drawings, and more particularly to FIG. l, one form of indicator tube according to the instant invention comprises an envelope 1 which has been evacuated of air and lled with an ionizable gas, such as neon, argon, or the like, at a suitable pressure, for example, in the range of about 40 to 120 mm. of mercury, and, if desired, one of the heavier gases or vapors, such as mercury. The envelope includes a base portion, or stem press, through which conductive base pins, or contact pins 2 extend, and by means of which electrical connection may be made to external electrical circuit means.

The tops of some, or all, of the contact pins 2 may be substantially coplanar, thus being adapted to support tube mount assembly 3 by means of the lower mica end spacer 4, the mount assembly being constrained against the tops of the base pins 2 by means, for instance, of clips such as shown at 17, which may be tweezerwelded to the top of one or several base pins, or by means of frictional engagement of lingers 5 on the mica end spacers 4 with the interior of the wall of envelope 1,- or both. It will be apparent to those skilled in the art that it may be necessary to shield the inner portions of base pins 2 associated with indicator cathodes 9, and the indicator cathode leads 10, from the anode-shield electrode base pins and leads. This may be done, for example, by coating the inner portions of base pins 2 and cathode leads 10 with glass frit, or Alundum, or by oxidizing the inner ends of the base pins and the leads 10, or any combination of these expedients found desirable by the tube designer. The envelope 1 also includes a transparent portion opposite cover mesh 18 (as shown in FIG. l) through which al1 of the the indicator cathodes in the envelope may be viewed, combined anodeshield electrodes 6 and 7 (see, for example, FIG. 3) and cover mesh 18 being provided with sufliciently large foramens to be substantially transparent. A sealed-off exhaust tubulation 11 is provided in the stem press of envelope 1.

The electrode elements of a tube according to the invention may be seen to include the following by comparison of FIGS. 1 and 3: a rst, or back, combined anode-shield electrode 6 made of conductive material, which may be foraminous to only a suicient extent to expose its associated indicator cathodes to view through the viewing portion of the envelope, or may be comprised to a larger degree, or entirely, of foraminous material. A second, or front, anode-shield electrode, like the back anode-shield electrode, may be wholly or only partly foraminous. A group of associated indicator cathodes is juxtaposed in association with each of said anodeshield electrodes, said anode-shield electrodes 'serving to excite the associated group of indicator cathodes or to shield the associated group of indicator cathodes against the effects of other electrodes, alternately.

The sputter shield 8 may be directly connected to the inner end of one of the base pins 2, which connection may serve to maintain the mount structure 3 in position longitudinally of envelope 1, either in insulated contact with the ends of the remaining base pins 2, or spaced therefrom.

The indicator cathodes 9 `of the tube m-ay take substantially any `desired shape, for example, they may be in the shape of numbers, letters, arbitrary symbols such as plus or minus signs, or the like. In one form ofthe tube, as shown in FIG. 4, the indicator cathodes may be provided in the form yof numbers, the total of such indicator cathodes being ten in number, including the num-bers 0 through 9. The indicator cathodes ymay be 'fabricated from any suitable metal, for example, stainless steel, aluminum, Nichrome, molybdenum, or the like; and they may be made in any suitable fashion, for example, by etching, stamping, forming from wire, or the like.

The indicator cathodes 9 are .mounted in an aligned stack as shown in exploded view in FIG. 3, such that their planes are substantially parallel, and are suitably shaped and of such size that the separate elements thereof are displaced laterally with respect to each other so that none is obstructed by the others, and each is' substantially completely visible through the wall of envelope 1- opposite cover mesh 18. In addition, each of the indicator cathodes within envelope 1 is provided, -by means of indicator cathode leads- 10, with connection to one of the 4base pins 2 other than those used for supplying potential to the combined anode-shield electrodes and the sputter shield electrode, one indicator cathode from the front group electrode, and one indicator cathode from the back group being connected in common to one of the base pins 2. The arrangement of the connections of the anodeshi- eld electrodes 6, 7, the sputter shield 8, and the indicator cathodes 9 with the base pins 2 is shown in FIG. 2.

FIG. 3 shows the several parts of a tube of the instant invention in exploded view. As may be seen from this figure, the mount structure 3 according to the instant invention is assembled by stacking a desired plurality of the indicator cathodes 9 and the combined anodeshield electrodes 6 and 7, the indicator cathodes and anode-shield electrodes Ibeing spaced apart by 4means of insulating spacing frames 13 and held in desired relation to the apertures in spacing frames 13 4by means of insulating positioning frames 14, 32. As will be apparent to those skilled in the art from consideration of FIG. 3 the stack made up Aof the indicator cathodes and combined anode-shield electrodes associated 4with a given sputter shield electrode 8 and the insulating spacing and -positioning frames associated therewith is assembled and inserted into the associated sputter shield electrode which first is closed at one end, and after the insertion of this stack the -cover mesh 18 at the iother end of the sputter shield electrode is' fastened in place (e.g., by means of spot welding) thereby maintaining the associated ndicator cathodes and combined anode-shield electrodes in desired spaced relation within the combined sputter shield electrode. As shown in FIG. 3, an opening 31 is provided in the bottom wall of the sputter shield electrode whereby the leads 10 of the indi-cater cathodes may pass through the sputter shield electrode without electrically contacting it. Leads 10 are preferably fabricated separately from the lower ears 12 of indicator cathodes 9, and then by welding or otherwise axed thereto at the proper angle to -pass out through channel 16 of insulating frames 14 (FIG. 5-b) clearing the edge of slot 31 of the sputter shield electrode structure by an amount determined to prevent spurious glow thereat. The insulating spacing frames 13 and the insulating positioning frames 14, 32 may be fabricated from many types of insulating material well known to those skilled in the art. Alternatively, due to the design of these frames according to the instant invention, these frames may be punched, stamped, etched, or otherwise formed from oxidiza-ble metallic materials, and then treated, e.g., by dipping in an oxidizing solution, and subjected to heating in an oven, thereby producing an insulating structure adapted for use as an insulator in carrying out the instant invention, which insulating structure has the advantage of being formed -by the simpler process available for producing metallic parts, as compared with the processes available for producing thin insulating parts. For instance, these insulating frames 13, 32, and 14 may be produced from sheet nickel which is rst electroformed, stamped, or punched, and then aluminized and oxidized, such a method being generally suggested in United States Patent No. 2,891,184.

After assembly the mount structure 3 may be adapted for positioning within tube envelope 1 by passing end micas 4 over the ends thereof as far as ears 24 provided on the longer sides thereof, passing ears 24 through slots 22 in the end micas, and bending the outer portion of the ears 24 along the outer surfaces of end micas 4, or distorting the outer portions as shown in FIG. 1. The completed mount assembly 3 and end micas 4 may then be assembled upon the base pins 2 in the stem press by welding the lower ears of the sputter shield electrode to one or more base pins 2, by means of clips 17, or both. The cathode leads and combined anode-shield electrode leads may then -be connecte-d to appropriate base pins 2, as by tweezer Welding, the stern and envelope sealed, and the envelope evacuated through tu-bulation 11, which is then sealed olf.

When assembled as described above, the indicator cathodes 9 will Ibe nonmutually-interferingly registered as shown in FIG. 4, wherein the cathodes making up the full set, 0 through 9 `are shown.

The contour of 1one of the insulating spacing frames 13 is shown in FIG. 5-a. It will be noted from this figure that the upper and lower edges of the frame aperture are provided with inwardly projecting portions which serve to maintain indicator cathodes 9 and combined anode- shield electrodes 6, 7 in spaced relation, and also serve to present only the numeral-defining portions of cathodes 9 to view through cover mesh 18.

The insulating positioning frames 14, 32 are illustrated in FIGS. S-b and 5-c. It will be noted from this ligure that the insulating positioning frames 14 are provided with inward projections of substantially the same contour as the inward projections in insulating spacing frames 13, but provided with ear receivers in which the ears 12 of the associated indicator cathode will be emplaced during assembly. Further, the insulating positioning frames 14 are provided with lead channels 16 communicating from one of the ear receivers 15 through the lower portion of the frame 14. As may be seen from FIG. 3, the indicator cathode leads 10 will pass through the channels 16, and will be constrained by the limited lateral extent of lead channel 16 from contacting the edges of slot 31 in the sputter shield electrode 8. It will be apparent to those skilled in the art that, by the provision of this particular lead channel structure and cooperating orientation and positioning of indicator cathode leads and combined anode-shield electrode leads 10, a controlled spacial relation between the indicator cathode leads 10 and the edges of slot 31 may be maintained, thereby taking advantage of the lower limb of the Paschens Law curve for mutual insulation purposes and assuring maximum isolation between the leads of adjacent cathodes.

FIG. 6 indicates an alternative construction which may be employed in a device according to the invention. In this alternative embodiment the combined anode- shield electrodes 6 and 7 have connected therebetween a pair of impedances 19 (usually equal) the common point of which is directly connected to sputter shield electrode 8 by means of connection 26. It will be apparent to those skilled in the art that, in certain circuits in which the tube ofv the invention may be employed, the potential thus applied to sputter shield electrode 8 will result in suppressing sputter upon the walls of the envelope, while not necessitating the use of an eighth base pin.

As will be apparent to those skilled in the art, the principles of the instant invention may also be embodied in a tube which includes more than two sets of groups of electrodes. A typical binary coded decimal counter system in which the tube of the instant invention may be employed is shown in United States Patent No. 2,906,906. Y y

Since numerous changes may be made in the abovedescribed apparatus, and dierent embodiments of the invention may be made without departing from the spirit thereof, it is intended that all the matter contained in the foregoing description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. An indicator tube comprising: a iirst group of indicator cathodes adapted to glow, a second group of indicator cathodes adapted to glow, an electrode associated with each of said groups of cathodes, said associated electrodes being at least partially located in the space between-said groups of cathodes, said space being otherwise free of electrodes, said electrode associated with said irst group of cathodes being adapted to excite at least one of said iirst group of cathodes to glow and being further adapted to prevent said first group of cathodes from glowing when any of said second group of cathodes is glowing, and said electrode associated with said second group of cathodes being adapted to excite at least one of said second group of cathodes to glow and being further adapted to prevent said second group of cathodes from glowing when any one of said irst group of cathodes is glowing.

2. An indicator tube comprising: a rst group of indicator cathodes adapted to glow, a second group of indicator cathodes adapted to glow, a combined anodeshield electrode associated with each of said groups of cathodes, each of said combined anode-shield electrodes being located adjacent its associated group of cathodes, the space between said combined anode-shield electrodes being free of electrodes, whereby each of said combined anode-shield electrodes is adapted to excite at least one of its associated cathodes to glow and is also adapted to shield its associated group of cathodes from glowing when any of the cathodes of the group associated with the other anode-shield electrode is excited to glow, and a sputter shield connected to voltage dividing means connected between said combined anode-shield electrodes, said cathodes, electrodes, sputter shield, and voltage dividing means all being contained within a common envelope.

3. An indicator tube comprising: a plurality of sets of groups of indicator cathodes adapted to glow and pairs of combined anode-shield electrodes interposed in the spaces between said groups of said sets, each of said combined anode-shield electrodes being adapted to excite at least one of its adjacent group of cathodes to glow and to coact in preventing its adjacent group of cathodes from glowing when any cathode of any of the other groups of its set is excited to glow by an adjacent combined anode-shield electrode, said spaces being otherwise free of electrodes.

4. An indicator tube comprising: a plurality of sets of groups of indicator cathodes adapted to glow and pairs of combined anode-shield electrodes interposed in the spaces between said groups of said sets, said spaces being otherwise free of electrodes.

5. An indicator tube comprising: a first group of five indicator cathodes adapted to glow, a second group of live indicator cathodes adapted to glow, a pair of combined anode-shield electrodes interposed between said groups of cathodes, the space between said groups of cathodes being free of further electrodes, and an envelope having at the most seven contact pins for making electrical contact between said cathodes and combined anodeshield electrodes and apparatus located externally thereof passing therethrough.

6. An indicator tube comprising: a plurality of sets of groups of indicator cathodes adapted to glow, pairs of combined anode-shield electrodes interposed between said groups of said sets, each of said combined anode-shield electrodes being adapted to excite at least one of its adjacent group of cathodes to glow and to coact in preventing its adjacent group of cathodes from glowing when any cathode of any of the other groups of its set is excited to glow by an adjacent combined anode-shield electrode, and an envelope enclosing said cathodes and cornbined anode-shield electrodes and having disposed therethrough n contact pins,- where and C equals the number of cathodes in one of said groups, S equals the number of said sets, and G equals the number of said groups.

7. An indicator tube comprising: a first group of indicator cathodes adapted to glow, a second group of indicator cathodes adapted to glow, and a pair of cornbined anode-shield electrodes interposed between said groups of cathodes, the space between said cathodes being otherwise free of electrodes, each of said combined anodeshield electrodes being adapted to excite its adjacent group of cathodes to glow and to prevent its adjacent group of cathodes from glowing when one or more of the otherr of said groups of cathodes is excited to glow by its adjacent combined anode-shield electrode, and coacting sputter shielding means comprising an insulating spacer member defining an enclosure at least partially enclosing said groups of cathodes and said combined anodeshield electrodes.

8. An electrode assembly for use in a glow indicator tube comprising: a plurality of indicator cathodes, a plurality of combined anode-shield electrodes, a first plurality of insulating frames surrounding each of said indicator cathodes and each of said combined anode-shield electrodes, a second plurality of insulating frames insulatedly spacing said first plurality of insulating frames, and a sputter shield engaging said frames, thereby maintaining said cathodes and anode-shield electrodes inV mutuallly fixed insulated relation without the use of other relation maintaining means. v

9. An electrode assembly for use in a glow indicator tube comprising; aplurality of indicator cathodes, a plurality of combined anode-shield electrodes, a first plurality of insulating frames surrounding each of said indicator cathodes and each of said combined anode-shield electrodes, a second plurality of insulating frames insulatedly spacing said rst plurality of insulating frames, and a sputter shield engaging said frames and clamping said frames, indicator cathodes, and combined anode-shield electrodes together, said frames, cathodes, and anodeshield electrodes being free of continuous members passing therethrough.

References Cited by the Examiner UNITED STATES PATENTS Re. 25,655 10/1964 McCauley et al. 313-1095 X 2,848,638 8/1958 Smith 313-1095 2,906,906 9/1959 McCauley et al. 313- 210 X GEORGE N. WESTBY, Primary Examiner.

D. E. SRAGOW, Assistant Examiner.

Claims (1)

1. AN INDICATOR TUBE COMPRISING: A FIRST GROUP OF INDICATOR CATHODES ADAPTED TO GLOW, A SECOND GROUP OF INDICATOR CATHODES ADAPTED TO GLOW, AN ELECTRODE ASSOCIATED WITH EACH OF SAID GROUPS OF CATHODES, SAID ASSOCIATED ELECTRODES BEING AT LEAST PARTIALLY LOCATED IN THE SPACE BETWEEN SAID GROUPS OF CATHODES, SAID SPACE BEING OTHERWISE FREE OF ELECTRODES, SAID ELECTRODE ASSOCIATED WITH SAID FIRST GROUP OF CATHODES BEING ADAPTED TO EXCITE AT LEAST ONE OF SAID FIRST GROUP OF CATHODES TO GLOW AND BEING FURTHER ADAPTED TO PREVENT SAID FIRST GROUP OF CATHODES FROM GLOWING WHEN ANY OF SAID SECOND GROUP OF CATHODES IS GLOWING, AND SAID ELECTRODE ASSOCIATED WITH SAID SECOND GROUP OF CATHODES BEING ADAPTED TO EXCITE AT LEAST ONE OF SAID SECOND GROUP OF CATHODES TO GLOW AND BEING FURTHER ADAPTED TO PREVENT SAID SECOND GROUP OF CATHODES FROM GLOWING WHEN ANY ONE OF SAID FIRST GROUP OF CATHODES IS GLOWING.

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