US2903624A - Cold cathode discharge tube - Google Patents

Description

Sept. 8, 1959 M. w. WALLACE COLD CATHODE DISCHARGE TUBE Filed Oct. 7, 1954 INVENTOR M/L/VEQ M WALZACE AGENT United States Patent 6 90 5% COLD CATHODE DIscHARGE TUBE Milner W- W l wes uq d, as ignor t nt national Telephone and Telegraph Corporation, Nutsy I i-"? s rp ates 9f Menard Application Qctober 7, 1954, Serial No. 460,877 Claims L 315-34 This invention relates to electron switching and counting devices and more particularly to multigap cold cathode discharge tubes for use in such devices capable of'effectively performing both counting and triggering functions.

In multigap tubes heretofore proposed for switching and countin'g'devices, an anode and several cathodes areprovided to 'form a number of cathode-anode gaps. In the use of these tubes, it is desired that the gaps discharge in a given order. It is also desirable that the discharge transfer reliably from one gap to another gap in some definite prescribed sequence. Such a multigap tube has been prepared and is described in my issued US. Patent 2,642,548. When such tubes are cascaded for purposes of sealer counting or frequency division, it is necessary to utilize theoutput pulse'from one tube to trigger the succeeding tube. A tube for such triggering has been described by G. H. Hough and D. S. Ridler in Multicathode Gas Tube Gounters appfi'ared in Electrical Comm sa isn S t mbe 1 0' However, neither of these prior art devices, as described in the above-mentioned patent and publication, can be us sr Psu s of i ss i f am triggering b hem el e A sent is bt frequency di si o ssalsr o nt n it s nsas s #6 f e the ou t Pu s m a ms ti sr Id ss sr us a ssss ti for mpl '4 U-S- 2s6 248i t a sing 9? m iss h fis t ig bs s st bsd in t e s p s ted P bli at n 1 tr ube s requ red in rde is mplify O u m' h counter tube. The output from the cbunter tube, after bei a lifi d b e t ia e? tu e is thsri te is o h sa er u s sm the e s. s q la r trigger ts if sm t re in us e s s to s st r tub and r r b and ultimately to a mechanical register or other device'de; p n u on the appli a ig desi e hu w r an extensive series of frequency divisien or sealer counting is us d. ma tub s ma be isa rsd' fsr P p s p p rfq m n b th h ss nt and r g n fu t sr' queutly, qu reme fa my tub m k s f iult ace s side a i l m s 't s he i' s sn ntm u e abora e W in and pro u q pr b ems .I use the te ms ha n in wit hin a d st ppin e e n a es en ia y ynq mq sg e n i re stricted herein to utilization of the output pulse of a counting tube to activate a second tube or'iother device.

On o the o je t 9f the P es m nna t pr vide a cold cathode gas-fired counting and switching tube capable of providing a triggering output pulse of much h he pow th n 1 .Q a sbl qm known 's s and switching gas tubes. v 4 v I Another object is to provide a tube performing both counting and triggering functions wherein output'circnit requirements ofpreviously known counting and trigger tube combinations are eliminated.

An additional object is to provide a novel type of directional cathode for the purposes of performing the foregoing counting and triggering functions.

One of the features of .this invention is that the counting function previously performed by one tube and the ice 2v r gerin fun i n re u psrfsrmsd y- 1, e mars other'tubes'are cooperatively and coactively interrelated so that'both functions are performed within the envelope of a single gas discharge tube.

' It is a further feature of this inyention that by eliminat ingthe loading efiect of the output cir cuit' of previously known counting; and trigger tube combinations, the counting' function can be performed more rapidly under less criticalcir'c'uit conditions, and the output frornthe counting tube is rendered suflicient to activate asueeeeu ingcounter tube without prior amplification by a trigger tubef It is another feature of this tube that a new electrode comprising a single loop of wire or a multi-looped spiral with its free end disposed to be primed by a discharge occurring in an adjacent cathode-anode gap is provided. The attached spiral portion serves to maintain the cathode g o The above-mentioned and other features and objects of this invention will become more apparent by reference to the following description taken in conjunction with the accompanying drawings wherein:

Fig. 1 is an elevational view in section of a multigap tube according to the present invention;

Fig.2 is a plan view partly in section of the tube shown in Fig. 1;

FigsfZA and 2B are sectional views taken along the lines 2A2A and ZBfZB, respectively, of Fig. l;

Figs 3 and 3A 'show'views 'in perspective of two em bodiments of a new type of directional electrode; and Fig 4 is a schematic View of the basic circuit of the 7 tubeof this invention.

Referring to Figs. 1, 2, 2A and 2B of the drawing, the tube comprises an envelope 1, preferably of glass or quartz, mounted in a base 2 which is provided with terminals 3 for reception in a socket. The terminals 3 are connected by leads 4 through the envelopel to corresponding electrodes of the tube. The base and envelope are secured together by cement 5. There is present a set of stepping glow cathodes 5 equispaced in a ci'rcl'llar or other reentrant array and facing the communicating passageway/s7 present "in the base of the cup-shaped first anode}. Thus, in a tube withfive counting positions, as illustrated in these figures, there would be ten of these cathodes 6. Each cathode 6 is provided preferably With a directional preference mechanism such as a Wire tail 9 for purposes of directing the discharge. A control plate or shield has not been shown, although one may be provided, as it not considered essential for the functioning ofthis tube." These cathodes 6 are connected electrically mehanically in two sets at their supporting insulating bases 10, made of a material such as mica, so that adjacent cathodes are not connected in the same set, but are in alternating arrangement. These connections are repreeented by bands (11 and 12 which also act as stops for the vertical location of the cathodes. Each set 'of these, cathodes is connected through a lead 13 to the tube base 2. This portion of the tube as described may be operated as a counting device in a manner similar to that described in my issued U.S. Patent 2,642,5{gi}. For obtaining the desired output for subsequent triggering of similar counting tubes or other devices following in sequence, an additional set of gaps 14 is provided. These gaps are formed by output cathodes 15 and a common second anode' 1 6. An eyelet 1701 similar mechanical device is used to attach the disk-shaped anode 16 to the central conductive post 18 and also insureelectrical contact of anode 1 6 therewith. An insulating sleeve 19 about the conductive post 18' is used to'prevent' discharges between this postand other conducting members within the tube envelope. Cathodes 15 are supported on a mica base 20 and connected tothe tube terminals'by means of conductive members 21 and leads 4. While for certain applications common anodes 6 and 16 may be combined into one anode, I generally prefer to use two separate common anodes. For the fiveposition switching tube illustrated, I have shown five of these output cathodes 15. These cathodes are positioned so that their tips are adjacent to or overlying the communicating passageways 7 in anode 8. For such a fiveposition tube, five of these passageways 7 may be provided: one over each of one group of electrically connected stepping glow cathodes 6. This group of cathodes may serve either as the transfer set, to which input pulses are applied, or as the storage set, depending on external connection of the tube.

In the tube illustrated, the stepping glow cathodes have been shown as provided with a directional preference mechanism, and divided into two groups of storage and transfer cathodes. For each cathode of one group of these stepping glow cathodes, an output cathode capable of delivering a triggering pulse has been provided. It will be apparent to those skilled in this art that for simple counting, for example, such a decimal counting, more than one output cathode per counting tube may not be required. Where the stepping glow cathodes are not provided with a directional preference mechanism the sequential stepping operation may be obtained by means of external circuitry. For such a tube construction, the number of output cathodes may vary up to as much as the total number of stepping glow cathodes. Where the stepping glow cathodes are directional and divided into two groups as illustrated in the figures, the maximum number of output cathodes will not ordinarily exceed the total number of stepping cathodes present in one group only.

In Fig. 3 is shown an enlarged perspective view of a novel type of cathode electrode 6a particularly suitable as a directional electrode. This electrode comprises a single-loop 22 of wire with the outer end 23 of the cathode disposed to direct the discharge occurring in an adjacent cathode to its own attached portion. It thereby serves to be primed by this adjacent discharge. The design of the electrode is such that the smaller portion 24 of the spiral will serve to maintain the cathode glow and in turn serve to prime the outer end 23 of the next cathode. In Fig. 3A is shown an enlarged view in perspective of a multiple-looped cathode 6b. The several loops 22a forming the cathode structure are in spiral shape and substantially within the same plane. The spiral is formed preferably in a closed form, with no spacing present between adjoining coils. Such a spiral arrangement oifers advantages over a helical spring-shaped cathode in that deionization times are hastened. Thereby an input pulse switching rate as high as 20-30 kilocycles per second may be attained. The more conventional cathodes are capable of input pulse rates of only about 2-5 kilocycles per second. The ability to switch at the higher rates broadens the useful field of application of these devices, as for example in the field of color television.

In Fig. 4 is shown a schematic manner of depicting the tube in a circuit. It will be seen that for proper operation of the tube, the voltages appearing on the elements of the tube should be in the following relationship:

where K refers to a cathode in set A of cathode 6, K refers to a cathode in set B of cathode 6, A is anode 8, K is output cathode i5 and A is output anode 16.

The operation of this tube is as follows, assuming K, to represent the transfer electrodes, i.e., those electrodes whose discharge is activated by a pulse input, and K represents the storage electrodes, those electrodes whose discharge occurs in the absence of a pulse. In Fig. 4 the communicating passageways have been shown as located over the transfer electrodes. When a particular will fire only during the input pulse.

transfer cathode 6 is conducting, the corresponding gap defined by cathode 15 and anode 16 are primed. The voltage on output gaps 14 is less than the normal striking voltage and greater than the prime striking voltage so that these gaps will be fired when they are primed. This results in a voltage rise in the output cathode resistor 25. The gap remains conducting until the next output gap is fired. Where it is desired to obtain a short output pulse, i.e., one that is less than the input pulse period, the cathode resistor 25 may be made large enough to extinguish the gap. Alternatively, the input pulse may be applied to anode 16 as well as to the input set of cathode 6, and the supply voltage reduced so that the output gap It is also possible to arrange the tube so that the count may be read by looking at the position of the glow and yet obtain a short output pulse. This may be accomplished by modifications in the external circuitry or by having the counting gaps visible.

While I have shown several possible cathode-anode assembly arrangements in Figs. 1 and 2, it will be clear that many other arrangements utilizing the simple cathode anode relationship and the assembly features of the present invention are possible. The cathodes 6, for example, may be arranged in any type of re-entrant array desired, regular or irregular, so long as the anode S is spaced equally from each of the cathodes 6 and one group thereof is properly positioned with respect to communicating passageways 7. Also, the cathodes 6 used may be formed in various shapes. For the attainment of high switching rates, as well as for simplicity of construction, the cathode embodiments 6a and 6b shown in Figs. 3 and 3A, respectively, are preferred. These cathodes may be conveniently fabricated from a tungsten wire as thin as .003 inch in diameter or from nickel or molybdenum wires of approximately .006 inch in diameter. Where directed sequential firing is not required, or is provided by external circuitry, the so-called tails 9 of cathodes 6 may be omitted. Thereby all cathodes 6 function as storage cathodw and half their number may be eliminated leaving an equal quantity of storage cathodes 6 and output cathodes 15. Where greater directivity is desired, the cathodes 6 may be fabricated in a cup-shaped manner, the glow discharge being thereby confined essentially to the hollow portion of the cathode. Such a structural arrangement will not provide as rapid a deionization time as that obtained with cathodes 6a and 612. Also, it is considered possible by suitable modifications in the external circuitry and in the structural arrangement of the tube to provide cathode-anode gaps by using a single common cathode and multiple anodes.

The gaseous atmosphere preferred for the tube is a mixture of neon, argon, and hydrogen, the percentages of which may be varied widely depending upon the gas pressure, the electrode voltages, the electrode geometry of the tube, and the breakdown voltage point desired. Where hydrogen gas is used in small percentages, the hydrogen accelerates deionization and is therefore desirable inasmuch as the counting speed limitations in a gas discharge device are set to a large extent by the deionization properties of the gaseous filling. Similarly, the tube geometry affects the degree of ionization coupling, i.e., the difierence in break-down potential of a gap measured in the unprimed and primed conditions. Generally, the amount of hydrogen preferred is between 5 and 10%. Argon is used principally to reduce the breakdown voltage point, and the amount present is not-critical. The percentage of argon is preferably between about 1 and 3%. The remaining component of the gas mixture is neon. Although the over-all gas pressure is not critical, relatively high pressures in the neighborhood of millimeters of mercury are preferred. The higher pressures generally favor more rapid deionization and also give a wider spread between normal striking and maintaining voltages.

I have described above the principles of my in;

vention in connection with specific apparatus, it is to be clearly understood that this description is made by way of example only and not as a limitation to the scope of my invention as set forth in the objects thereof and in the accompanying claims.

I claim:

1. A discharge device comprising a hermetically sealed envelope containing a gaseous atmosphere, a first anode, an array of stepping glow cathodes spaced apart from said anode to provide a series of cathode-anode gaps, a second anode, at least one output cathode galvanically separated from said glow cathodes and spaced apart from said second anode to provide at least one output cathode-anode gap, said output cathode-anode gap being in a coactive relation to a selected one of said series of cathode-anode gaps and capable of being discharged upon occurrence of a discharge in said selected one.

2. A discharge device according to claim 1 including means electrically connecting said stepping glow cathodes in two groups with the cathodes of the two groups in alternate relation.

3. A discharge device according to claim 1 wherein said first anode is interposed between said array of stepping glow cathodes and said output cathodes, said anode including communicating means between a stepping glow cathode and an output cathode.

4. A discharge device comprising a hermetically sealed envelope containing a gaseous atmosphere, a first anode, an array of stepping glow cathodes spaced apart from said anode to provide a series of cathode-anode gaps, means electrically connecting said stepping glow cathodes in two groups with the cathodes of the two groups in alternate relation, a second anode, a plurality of output cathodes galvanically separated from said glow cathodes and spaced apart from said second anode to provide a plurality of output cathode-anode gaps, said output cathode-anode gaps being in a coactive relation to respective selected ones of one group of said series of cathode-anode gaps and capable of being discharged upon occurrence of a discharge in said selected ones.

5. A discharge device according to claim 4 wherein said stepping glow cathodes include means defining a directional preference mechanism.

6. A discharge device according to claim 5 wherein said means defining a directional preference mechanism comprise a looped spiral wire with its outer end disposed to be primed by a discharge at an adjacent glow cathode, the loops of said spiral being maintained substantially within the same plane.

7. A discharge device according to claim 4 wherein all said stepping glow cathodes include means defining a directional preference mechanism comprising a multilooped spiral whose loops all lie substantially in the same plane and whose outer end is disposed to be primed by a discharge at an adjacent glow cathode and wherein said first anode is interposed between said array of stepping glow cathodes and said output cathodes, said first anode including communicating means between the cathodes of one group of electrically connected stepping cathodes and respective output cathodes.

8. A discharge device comprising a hermetically sealed envelope containing a gaseous atmosphere, a first anode, a re-entrant array of an even number of stepping glow cathodes spaced apart from said anode to provide a series of cathode-anode gaps, means electrically connecting said glow cathodes in two groups with the cathodes of the two groups in alternate relation, a second anode, a plurality of output cathodes galvanically separated from said glow cathodes equal in number to the stepping glow cathodes of one electrically connected group of said stepping glow cathodes, said output cathodes being spaced apart from said second anode to provide a plurality of output cathode-anode gaps, said second anode being interposed between said stepping glow cathodes and said output cathodes, said first anode having communicating means disposed between the cathodes of one group of electrically connected stepping cathodes and respective output cathodes to provide a coactive relationship between one group of the series of stepping cathode-anode gaps and respective output cathode-anode gaps whereby said output cathode-anode gaps are capable of being discharged upon occurrence of a discharge in said corresponding cathode-anode gaps defined by one group of stepping glow cathodes and said first anode.

9. A discharge device according to claim 8, wherein said first anode is a cup-shaped member having a substantially flat base section and wherein said communicating means in said first anode comprise passageways in reentrant array in said base positioned adjacent the cathodes of one group of electrically connected stepping glow cathodes.

References Cited in the file of this patent UNITED STATES PATENTS 2,553,585 Hough May 22, 1951 2,687,496 Wales Aug. 24, 1954 2,690,525 Koehler Sept. 28, 1954 2,785,355 Gugelberg Mar. 12, 1957 2,790,110 Applegate Apr. 23, 1957

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