US2740921A - Electric discharge tubes and circuits therefor - Google Patents

Description

April 1956 G. H. HOUGH ET AL 2,740,921

ELECTRIC DISCHARGE TUBES AND CIRCUITS THEREFOR Filed Dec. 11, 1951 INVENTOR GHHOUGH TMJACKSON ATTORNEY United States Patent Office 2,740,921 Fatented Apr. 3, 1956 ELECTRIC DISCHARGE TUBES AND CIRCUITS THEREFGR George Hubert Hough and Thomas Meirion Jackson, London, England, assignors to International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Application December 11, 1951, Serial No. 261,086

Claims priority, application Great Britain December 1.2, 195d 2 Claims. (Cl. 315-84.6)

This invention relates to multi-gap cold cathode gasfilled electric discharge tubes, and has for its object to provide a circuit arrangement for such a tube having a high input impedance capable of responding to low power pulses.

The main feature of the invention comprises an electric impulse responsive device comprising a pair of gasfilled electric discharge tubes forming a binary counting stage and having a high impedance and capable of responding to electric impulses having a relatively low current level and generating pulses having a relatively high current level and a multi-gap cold cathode gas-filled electric discharge tube connected directly to the pulse output of said tube pair.

The invention will be described with reference to certain embodiments shown in theaccompanying drawings in which:

Fig. 1 shows a circuit arrangement in which a pair of cold cathode gas-filled electric discharge tubes forming a binary counting stage receives electric pulses at its input and feeds them alternatelyto two interleaved sets of cathodes in a multi-gap cold cathode gas-filled electric discharge tube, while Fig. 2 shows a circuit arrangement in which a pair of cold cathode gas-filled electric discharge tubes forming a binary counting stage receives incoming pulses and feeds corresponding pulses to the common anode of a cold cathode multi-gap gas-filled electric discharge tube.

Fig. 3 shows the pulse forms at various stages in the operation of Fig. 2.

The circuit of Fig. 1 consists of a flip-flop tube pair CTl/CTZ which responds to a supply of positive pulses delivered to terminal P and, in turn, causes stepping of the anode/cathode discharge in the gas-filled cold cathode multi-gap discharge tube MCT.

The flip-flop tube pair functions in normal manner, alternate pulses applied to the point P causing the pr viously unfired tube of the pair to become conducting and the other tube to be extinguished. The cathode potential of the conducting tube rises so that with leads L1, L2 taken from the two cathodes of the tubes CT 2 and GT1 respectively, positive potentials can be delivered directly to the multi-gap tube MCT in turn over the two leads L1 and L2. The multi-gap tube MCT has all its cathodes arranged in a ring.

The tube MCT contains an array of cathodes which cooperate with a common anode, each cathode defining a separate glow discharge gap with the anode, and is of the type described and claimed in U. S. Patent No. 2,604,602 to G. H. Hough. All the individual cathodes are of the same directional type, that is to say they have extensions in one direction so that discharge from a first cathode tends to ionise the gap bounded by the adjacent cathodes on the side of the extension of the first cathode and not the gap bounded by the adjacent cathode on the other side of said first cathode. The cathodes are multiplcd together in two interleaved sets so that all odd numbered cathodes 1, 3, 5, etc, are connected 2 to a single multiple connection 0C and all even numbered cathodes 2, 4, 6, etc. are connected to another single multiple connection, EC. The leads L1, L2 are connected via decoupling resistances R1, R2 each to a respective one of the sets of cathodes of MCT. Assume that gap 1 is originally discharging. With tube CTl initially conducting, the first pulse to be applied to terminal P causes CT2 to become conducting and GT1 to extinguish. By this means, the positive potential on lead L1 is increased, so that the potential across gap 1 is decreased, while the potential on lead L2 is decreased so that the potential across gap 2 is increased. The discharge in gap 1 is extinguished over a short period and the discharge is transferred to gap 2. Successive pulses on terminal P each reverse the conditions of tubes CTl, CT2 and the potentials on leads Li, L2 so that each pulse on P results in transfer of the discharge in MCT to the next gap. Thus the successive pulses on P are transformed into alternate pulses on leads L1, L2, which cause the stepping of the discharge in MCT from gap to gap in synchronism with the pulses on P.

The pulses on P can be at very low current level, but the tube pair CTl, CT2 produces comparatively high level current pulses on leads L1, L2 capable of driving tube MCT.

Fig. 2 shows an anode-driven counter in which a tube pair of three-electrode cold cathode gas tubes CTA, CTB forming a binary counting stage, is used to drive a multi-gap counter tube MCA. 1

As before, the input impedance of the tube pair is high and the pair is capable of responding to pulses of very low current level.

Counting pulses are applied at input TPl to the trigger electrode of the tubes CTA, CTB in parallel via resistors R1, R2. Each pulse causes the conducting tube to extinguish and the other tube to discharge. Assuming a positive input pulse wave form P1, Fig. 3, a wave form P2 of negative potential appears at TDZ on the common anode lead, due to the charging of the cathode capacitors CCA, CCB. The P2 pulses are applied via capacitor TC to the anode of multi-gap tube MCA which is of the same type as MCT, Fig. 1 having a series of like directional cathodes DCl, DC2 Interleaved sets of alternate cathodes DCl, DC3 DCZ, D04 are multipled together and via respective resistance-capacity networks RC1, RC2 are connected to earth. Each pulse extinguishes the existing discharge across one gap of MCA, and due to the well known combined effect of the common anode resistor CAR and the RC networks RC1, RC2 the next gap fires on the termination of the pulse and prevents the previously fired gap from again discharging. The operation is fully described in U. S. Patent No. 2,533,585 to G. H. Hough. As before, the pulses P2 have a current level many times higher than the pulses P1 and have a power content sufiicient to drive MCA.

In each case the tube pair could be thyratrons.

While the principles of the invention have been described above in connection with specific embodiments and particular modifications thereof, it is to be clearly understood that this description is made only by way of example and'not as a limitation on the scope of the invention.

What we claim is:

1. An electric impulse-responsive device comprising a pair of gas-filled electric discharge tubes forming a binary counting stage, said stage having a single high impedance input and being capable of responding to electric impulses at a relatively low current level and having a pair of outputs, said stage adapted to generate an output impulse alternately on said outputs for each input impulse said output impulses having a relatively high current level, a multi-gap discharge device comprising electrode means defining an array of separate glow'discharge gaps first means interconnecting alternate of said gaps and second means interconnecting intervening of said gaps, and means for applying output im pulses from the outputs of said stage to said first and second means, respectively, whereby the discharge of said device is stepped along said array in synchronism with the pulses incoming to said stage over said single input.

2. An electric impulse responsive device, as claimed in claim 1, in which the two outputs of the tube pair of the binary counting stage are connected to the respective cathodes of said tubes, so that transfer of discharge from one tube to the other of said pair will result in a rise in potential on one cathode lead and a reduction in potential on the other cathode lead, the multi-cathode discharge device having a common anode and a series of closely-spaced, similar, directional cathodes, substantially equally spaced from said common anode, the means for applying alternate output impulses from the outputs of said binary stage to the first and second interconnecting means comprising separate connections between 5 said outputs and said first and second connecting means.

References Cited in the file of this patent UNITED STATES PATENTS 2,505,006 Reeves Apr. 25, 1950 FOREIGN PATENTS 486,752 Canada Sept. 23, 1952 OTHER REFERENCES

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