US3012166A - Gas discharge vessel - Google Patents

Description

Dec. 5, 1961 KARL-HEINZ RUMPF ETAL 3,012,166

GAS DISCHARGE VESSEL 2 Sheets-Sheet 1 Filed March 26, 1956 ATTO R N EYS Dec. 5, 19%

Filed March 26, 1956 Tuclj- Uy I KARLHEINZ RUMPF ETA].

GAS DISCHARGE VESSEL 2 Sheets-Sheet 2 Impulse Gene/afar ATTO R N EYS nited States 3,012,166 Patented Dec. 5, 1961 doc 3,012,166 GAS DISCHARGE VESSEL Karl-Heinz Rnrnpf, Fredersdorf, near Berlin, and Roland Gessner, Berlin, Germany, assignors to VEB Werk fiir Fernmeldewesen, Beriin-Gberschonweide, Germany Filed Mar. 26, 1956, Ser. No. 574,359 15 Claims. (Cl. 313-493) The invention relates to a gas discharge vessel, and more particularly to a gas discharge vessel or tube having a cold cathode and which is particularly suitable as switching means in an electronic communication exchange.

It is known that present gaseous discharge electron tubes can not be controlled similarly to electron vacuum tubes by means of a grid electrode. Generally, the discharge in a cold cathode gaseous tube is initiated by raising the voltage between the anode and the cathode to a value greater than the ignition voltage and the discharge can be extinguished only by lowering the anode cathode voltage to a value less than the glow voltage of the tube. In thyratron tubes, a discharge may be initiated from the thermionic cathode by reducing the control grid bias, but here again, the discharge can be extinguished only by lowering the anode voltage below the value of the glow voltage.

An object of the present invention is to provide a cold cathode gaseous discharge tube in which the grid is formed and located with respect to the anode and the cathode so that the discharge in the tube can be ignited and extinguished merely by applying a small control voltage to the grid, which is small relative to the anode voltage, such control of the gaseous discharge being efiected without controlling the anode voltage.

Another object of the invention is to provide a cold cathode gaseous discharge tube alternating current amplifier in which the discharge current is responsive to a small alternating voltage applied to the control grid of the gaseous discharge tube.

Further objects and advantages of the present invention will be apparent from the following detailed descrip tion thereof in connection with the accompanying drawings showing, by way of example, some embodiments of the present invention. In the drawings FIG. 1 is a perspective view of a first embodiment of the invention, the front part of the device being removed, the remaining parts being cut in the plane CD of FIG. 2,

FIG. 2 is a horizontal section taken along the line A-B shown in FIG. 1,

FIG. 3 is a perspective view similar to FIG. 1 of a second embodiment of the invention, the cut shown in FIG. 1 being made along the line G.-H shown in FIG. 4, I

FIG. 4 is a horizontal section of the device shown in FIG. 3 of the line EF of FIG. 3,

FIG. 5 is a diagrammatic illustration of a circuit having a tube according to the invention,

FIG. 6 is a diagram for the explanation of shown in FIG. 5,

FIG. 7 is a circuit diagram illustrating the connection of another embodiment of the present invention, and

FIG. 8 is a wiring diagram illustrating another application of a tube according to the invention.

Referring now to the drawings and first to FIGS. 1 and 2, a discharge vessel or tube of which only the base 1 is shown is provided with a cold cathode 4 shaped as a cylinder and connected to the base 1 by a relatively short wire 10 and'a relatively long wire 11 passing through the base 1, and serving as a potential lead to the cathode. The cathode 4 surrounds, as shown, the other electrodes the device to be mentioned presently, and is arranged between two circular mica sheets 2 and 8 joined with each other by rods 7 which are connected, respectively, with wires 10 and 11.

An auxiliary anode 3 shown in FIG. 1 as a ring-shaped wire is arranged on two supports 12 and 13 connected, respectively, with wires 15 and 16 which are connected after passing through the base 1 to form a single connection 17 for applying a positive potential to the auxiliary anode 3. Instead of being shaped as a ring .the auxiliary anode might also be shaped as a cylinder or, as shown in FIGS. 3 and 4, two rods the ends of which are held by the mica sheets 2 and 8.

Furthermore, a grid-like electrode 5 is supported by two rods 18 and 19 supported in turn by the mica sheets 2 and 8. The supporting rod 18 is connected with a wire 20 passing through the base 1 downwards. Furthermore, a main anode 6 shaped as a rod arranged along the axis of the cathode 4 and the grid-like electrode 5 is supported by the mica sheets 2 and 8 and connected with a wire 21 passing through the base 1. The whole is enclosed by a vessel (not shown) forming an envelope or tube which is flied with a gas or a vapor.

Referring now to FIGS. 3 and 4, the design of the gas discharge tube is essentially the same as that of the tube shown in FIGS. 1 and 2, and therefore only the differences shall be described more in detail hereinafter. The first difference resides in that the cathode 4' is shaped as a body having two opposite plane walls 22 and 23 connected by part cylindrical walls 24 and 25, furthermore, a second grid-like electrode 9 is arranged coaxially with and inside the grid-like electrode 5. Furthermore, the auxiliary anode is formed by two rods 3' and 3" extending parallel to the main anode 6 in the space between the cylindrical surfaces 24 and 25 and the grid-like electrode 5. The two rods 3 and 3" extend through the mica sheet 2 downwards into the base 1 and are connected by the connections 15 and 16 with the single connection 17.

The operation of the gas filled tubes shown in FIG. 1 to 4 is as follows:

The anode 6 is maintained by the DC. source, such as a battery 23 under a direct potential relative to the cathode 4 or 4'. The grid-like electrodes 5 or 9 are given a direct voltage, an alternating voltage or an impulse voltage termed hereinafter a control voltage. If this control voltage or voltages, the source of which is not shown in FIGS. 1 and 3, are given a value imparting to the electrons together with the penetrating potential field of the anode an energy which is suflicient to enable electrons to pass through the grid and form a plasma, the discharge vessel will be ignited. When the control voltage is reduced to the initial value the tube will be extinguished since the grid-like electrodes form isles preventing the flow of electrons in the grid anode space so that the onization is not maintained. Since no new electrons are formed at the cold cathode after finishing the discharge because a potential field sufiiciently strong for overcoming the work function does not exist at cathode 4, 4. The plasma on the grid-like electrodes having a control potential lower than that of the anode becomes exhausted so that the tube is extinguished without decreasing the anode voltage below the operating voltage of the tube. Thus, if the tube is used in a relay, the means for extinguishing the tube are considerably reduced.

If it is intended to reduce the magnitude of the change of the control voltage, or expressed in other terms, if the ability of the tube to respond has to be increased, the same may be accomplished by means of a preionization in the cathode-grid space. In order to accomplish this, the auxiliary anode 3 in FIGS. 1 and 2 or the auxiliary anodes 3 and 3" in FIGS. 3 and 4 are arranged near the cathode and are given a slightly positive potential with respect to the cathode 4 or 4' as indicated by connecting the conductor 17 with a cell C near the negative terminal of the battery B. ,In consequence thereof the auxiliary anodes 3, 3 3" maintain an uninterrupted auxiliary discharge forming a plasma having the effect of a permanent source supplying electrons or ions which thus is equivalent to the emitting cathode 4 or 4', Thus, the operation of such a tube at the beginning and end of a discharge is comparable to that of a tube having a hot cathode. In other words, the grid-like electrode or electrodes 5 and 9, which are imparted a potential below the operating voltage of the auxiliary discharge, prevent by the formation of isles the entry of electrons in the gridanode space of the tube, and therefore an ignition thereof. 'Only at a corresponding value of the control voltage the potential field causing the formation of isles becomes sufiiciently low, so that the kinetic energy of the electrons sufiices for a piercing of the formation of isles so that the tube is ignited. The end of the discharge is effected by an increase of the potential field of the isle forming control electrons so that the electrodes may no longer pierce the potential field, the plasma in the gridanode space being broken up so that the discharge is finished. For a satisfactory operation of these tubes the size of the openings of the grid-like electrodes should be smaller than the length of the free path of the ions and electrons.

The permanent auxiliary discharge may be tolerated since the same involves only currents of an order of a few hundreds of micro-amps. Thus, the input of several hundreds of these tubes is not larger than that of a single tube having a hot cathode.

Tests made with the discharge vessel according to the invention have proved the correctness of the facts pointed out hereinabove. If desired, more grid-like electrodes may be provided as shown hereinafter in connection with FIG. 7, these electrodes forming blocking electrodes or initiating electrodes which allow to realize almost all switching possibilities occurring in communication circuits or controlling technique such as relay circuits, coincidence circuits, anticoincidence circuits, and circuits with a continuous grid control such as amplifier circuits;

Referring now to FIG. 5, a wiring diagram of a gas filled tube 30 is shown having a cathode 32 connected to ground 34, and an anode 36 connected through a resistor 38 with a positive direct potential. The grid 40 of the tube 30 is connected over a condenser 42 with a source U of an alternating voltage. A source of a direct voltage U is connected through a resistor 44 with a point 46 intermediate between the grid and the condenser 42. Rectangular impulses are taken from the anodes 36 by a connection 46 connected with an intermediate point 48 of the anode 36 and the resistor 38.

The operation of this device is as follows:

The alternating voltage U supplied to the condenser 42 connected with the grid-like electrode 40 is relatively high with respect to the direct voltage U supplied over the resistor 44 to the grid-like electrode 40. In consequence thereof the tube is caused to ignite and to extinguish according to the alternating voltage U fed to the grid-like electrode 40. At the anode 36 rectangular voltage impulses are generated thereby which are taken off the tube 30 by the connection 46. The ratio of the impulses and the gaps separating the latter may be arbitrarily changed by adjusting the direct voltage U and it is even possible to suppress entirely the rectangular voltage impulses taken from the connection 46.

FIG. 6 is a diagram in which the grid voltage U is plotted on the horizontal negative axis, whereas the anode current I is plotted on the vertical axis of the system of coordinate shown in FIG. 6. An alternating voltage U is superposed to the grid voltage U and the curve K shown in heavy lines shows the characteristic of the tube 30. 7 It will be seen that the characteristic K consists of a part L coinciding with the horizontal axis, a part M vertical to the horizontal axis, and a slightly increasing part N. The part L extends over the negative half waves and half the positive half wave of the alternating voltage U and only during the highest part of the positive half wave of the alternating voltage U the anode current shown by the characteristic K increases suddenly in the part M to the part N representing an impulse O occurring in the connection 46.

Also a saw-tooth voltage may be used for igniting and extinguishing the tube shown in FIG. 5. The width of the impulse generated in this case is also a function of the bias applied to the grid-like electrode 40. When in such an arrangement an alternating voltage is again superposed to the grid bias, said alternating voltage having a frequency being low against that of the saw-tooth voltage, rectangular impulses will be generated at the output circuit of the tube, said impulses having a frequency corresponding to that of the saw-tooth voltage and a width corresponding to instantaneous values of the amplitudes of the second alternating voltage. Thus, this phenomenon represents a time modulation.

if the impulses occurring at the output of the tube are differentiated, and then imparted with the variable flank thereof as an igniting and extinguishing impulse, to a further discharge vessel according to the invention, impulses of a constant frequency, amplitude and width are encountered in the output circuit of the latter discharge vessel, said impulses having a phase position coinciding with the instantaneous values of the second alternating voltage. Thus this phenomenon corresponds to a phaseimpulse modulation. The expenses for these modulations circuits are considerably lower than those for the known circuits for the aforementioned kinds of modulation.

Referring now to FIG. 7, a coincidence circuit is shown with subscribers loops in an electronic exchange designed as a coordinate exchange. The subscribers are allotted cables having three conductors a, b, c, or a, b, 0, respectively. The conductors a, b, and a, b, are speech conductors which may be connected with each other by the contacts t, t' of a relay T inserted into the connection 50 connecting the anode 52 of a gas filled tube 54 with a battery and the grounded cold cathode 56 of the tube 54. I

The conductors c and c carry impulses characteristic of the respective subscribers and having a rectangular shape. The rectangular impulses are produced in a centrally arranged impulse generator. The tube 5-4 has three grids 58, 60, and 62 arranged between the cold cathode 56 and the anode 52. The grid 58 is connected by a conductor 64 with the conductor 0, the grid 60 is connected by'a conductor 66 with the conductor c. The grid 62 is connected by a conductor 68 with a conductor 70 carrying another impulse sequence characterizing the I connection to be efiected by the tube 54 as free or engaged, thus implementing a coincidence-anticoincidence efiect.

The operation ofthis device is as follows:

Under ordinary conditions the tube 54 does not carry any current since the grid- like electrodes 58, 60, and 62 thereof are not imparted any control voltages from the conductors c, c or 70. However, when impulses characteristic for the first subscriber represented by the conductors a, b, c, are imparted to the conductor c by the central impulse generator in cooperation with an impulse sequence imparted to the connection c" of the second subscriber by the central impulse generator (not shown), the tube- 54 becomes conductive so that the relay T' is energized and connects with the contacts t, t thereof, the speech conductors a, b of the first subscriber with the speech conductors at, b of thesecond subscriber. The saw-tooth voltage imparted to the conductor 70 and transmitted to the third grid-like electrode 62 has the effect that the connecting elements T, t, t associated with the tube 54 are characterized as free or engaged as the case may be. When the conversation between the two subscribers is finished the grid- like electrodes 58, 60, and 62 interrupt the flow of current through the tube 54 and the relay T connected in the anode circuit thereof.

In a tube such as that shown in FIGS. 3 and 4 provided with two grid-like electrodes 5 and 9, the occurrence of an impulse on one of the electrodes will cause the tube to ignite, whereas the occurrence of the impulse on the other of the grid-like electrodes will extinguish the tube. However, it should be noted that in the embodiments shown in FIGS. 14, special forms of the electrodes of the tubes and special arrangements thereof are shown, whereas, in the embodiments shown in FIGS. 5, 7, and 8, the arrangement of the cathode, the gridlike electrode or electrodes, and the anode is of a conventional kind.

Referring now to FIG. 8, an arrangement is shown in which the ignited tube operates simultaneously as an amplifier. The gas filled tube 86 includes a cathode 82 connected to ground, a grid-like electrode 84, and an anode 86. An anode resistor 88 connected to the anode 86 is connected to a supply of a direct anode voltage. A conductor 90 is connected to a point 92 between the anode 86 and the anode resistor 88. The grid-like electrode 84 is connected by a connection 94 with a condenser 96 connected to a terminal 98 to which an alternating voltage U having a relatively small amplitude to be amplified is applied. The conductor 94 is connected with a conductor 100 connected over a grid resistor 102 to the movable contact 104 cooperating with stationary contacts 106 and 108 which are connected, respectively, with a terminal 110 and a terminal 112. To the terminal 112 a voltage U is applied eifecting an ignition of the gas-filled tube 80, whereas to the terminal 112 a direct voltage U is applied which effects the extinction of the gas-filled tube 80. In operation, the alternating voltage U supplied to the terminal 98 is amplified by the tube 80 as long as the latter is ignited, so that in the conductor 90 an amplified alternating voltage U is obtained.

In a tube having a cold cathode it is impossible to end the discharge by applying a countervoltage to the control electrode. In order to accomplish this, the anode voltage has to be lowered below the ignition voltage which may be efiected by applying an alternating voltage or a strong negative voltage impulse to the anode. However, this can only be accomplished with considerable switching means which are avoided in the tubes and the connections according to the present invention.

It is seen from what has been said hereinbefore that the invention provides a gas filled discharge vessel or tube having a cold cathode, said discharge vessel being free of the defects of the discharge vessels known in the art, a particular advantage of the tubes according to the present invention being that the gas discharge may be finished while the anode voltage is applied. In general terms the present invention relates to a gas discharge vessel or tube in which with a direct voltage connected to the anode the gas discharge is started and terminated by changing the values of a voltage or potential applied to a grid-like electrode.

The favorable efiects obtainable thereby have been described hereinabove in connection with the operation of the embodiments of the invention shown in FIGS. 1-4.

Tests carried out with a discharge vessel according to the present invention have shown that the anode current thereof is suflicient for commanding any control actions occurring in practice in remote signaling or control devices.

A preionization may be efiected, for instance, by means of a high-frequency field acting upon the gas filling the discharge tube.

With a plurality of grid-like electrodes the invention may be carried out with a direct voltage applied to the anode by starting or terminating the gas discharge by changing at least one voltage or potential applied to the grid-like electrodes. However, it is also feasible to start or extinguish of the gas discharge by changing the value of the voltage applied to one of the grid-like electrodes, and to prevent or start the discharge by a simultaneous change of the values of the voltages or potentials applied to a plurality of grid-like electrodes.

By this means it is accomplished that the discharge vessel according to the present invention may be operated as a coincidence tube, an anticoincidence tube, or as a normal tube.

The present invention may be realized with a plurality, for instance three grid-like electrodes, and a direct voltage applied to the anode, by starting or extinguishing the gas discharge at a constant value of one of the control voltages, and changing the values of the other control voltages applied to the grid-like electrodes, and to prevent or start the gas discharge by changing the values of all control voltages.

By these means it is accomplished that the gas discharge vessel according to the invention acts in relation to the differently controlled circuits, simultaneously as a coincidence tube, an anticoincidence tube, and a normal tube.

Tests carried out with tubes according to the invention have shown that in the ignited state of the discharge vessel, according to the invention, the operating voltage thereof, and thus the anode current may be changed by means of one or more of the control voltages. During the discharge the control voltage may be adjusted in a simple manner, for instance, by means of a potentiometer or the like. If a direct voltage is used as a control voltage, as indicated in FIG. 8, and this direct voltage is superposed by an alternating voltage having a small amplitude, this alternating voltage being applied to the terminal 98, the anode current follows the frequency and amplitude of the superposing alternating voltage applied to the terminal 98. The dependence of the anode current on the superposing alternating voltage has the advantage that, for instance, an audio-frequency voltage apphed to the grid 84 of the ignited tube appears correspondingly amplified in the output circuit of the tube.

The discharge vessel according to the present invention may be used with advantage as a coupling element in alternating voltage circuits, for instance, audio-frequency circuits of electronic selector circuits, as shown hereinabove in connection with FIG. 7, such a use being impossible with the cold cathode tubes known in the art.

Also, by means of the discharge tube according to the invention, circuits and particularly control circuits in electronic selector circuits may be directly closed and opened, which was hitherto realized, with the full anode voltage applied, only by means of particular connections generating extinguishing impulses. The use in electronic selecting circuits has great advantages consisting, apart from saving the heating power and special devices for the withdrawal of heat, in that when a direct voltage is applied as a control voltage, and a rther direct voltage as anode voltage, no humming is transferred to the long distance line.

We have described hereinabove preferred embodiments of gas filled discharge vessels or tubes and connections using the same. However, we wish it to be understood that many changes, alterations, or substitutions of equivalents may be made in the tubes and the connections thereof described hereinabove without sacrificing any of the inherent advantages of the present invention which is defined by the appended claims.

We claim:

1. A gas glow discharge tube comprising an envelope enclosing a cold cathode, a grid electrode and an anode, grid electrode means located between the anode and the cathode and formed so as to be opaque to electrons and ions in response to a given grid electrode biasing voltage relative to the cathode, and means including said grid a e electrode means for initiating and extinguishing a gaseous glow discharge between the cathode and the anode in response to biasing voltages on the grid electrode relative to the cathode which are less than the low voltage of the tube and while the anode is at a positive voltage with respect to the cathode which is in excess of the glow voltage.

2. A gas glow discharge tube comprising an envelope enclosing a cold cathode, a perforated grid electrode and an anode, said grid electrode being located between the cathode and the anode and formed so as to separate the anode from the cathode, the perforations in the grid electrode having a size smaller than the length of the mean free path of the ions and electrons, whereby said grid electrode is capable of initiating and extinguishing a gaseous glow discharge between the anode and cathode in response to a control voltage which is smaller than the glow voltage of the tube.

3. A gas glow discharge tube comprising an envelope enclosing an anode in the form of a rod, a cylindrical grid electrode surrounding the anode, the openings in the grid electrode being smaller than the length of the mean free path of the electrons, a cylindrical cold cathode surrounding the grid electrode and control means including said grid electrode for extinguishing a gaseous glow discharge between the cathode and the anode in response to a control voltage applied between the grid electrode and cathode which is less than the glow voltage and while a voltage at least equal to the glow voltage is applied between the anode and the cathode.

4. A gaseous glow discharge tube according to claim 3, wherein said control means includes a plurality of coaxial cylindrical grid electrodes interposed between the cathode and the anode.

5. A gaseous glow discharge tube according to claim 3, including an auxiliary anode located between the cathode and the grid electrode for maintaining a continuous gaseous discharge between said cathode and said auxiliary anode in response to a steady voltage connected therebetween. V V

6. A gaseous glow discharge tube according to claim 5, wherein said auxiliary anode and said steady voltage are dimensioned to produce a current of the order of a few hundred microamperes.

7. A gaseous glow discharge device comprising a gas discharge tube having an envelope, an anode, voltage supply means for applying a voltage between the anode and the cathode which is in excess of the ignition voltage of said tube, and means for initiating and extinguishing a gaseous glow discharge between the anode and the cathode while said voltage supply means is connected therebetween, said means including a grid electrode located between said anode and cathode, the openings in said grid electrode being of a size smaller than the length of the mean free path of the electrons, and means for applying a biasing voltage between the grid electrode and the cathode which has a value less than the voltage on said anode.

8. A device according to claim 7, including means for impressing an alternating current signal between the control electrode and the cathode and means connected to the anode for deriving an alternating voltage output therefrom. V

9. A deviceaccording to claim 7, including means for maintaining a continuous gaseous discharge from said cathode, said last means comprising an auxiliary anode located between the cathode and the grid electrode and a source of voltage connected between the cathode and the auxiliary anode.

10. A device according to claim 7, including a plurality of control grids and means for supplying control voltages to said grids.

11. A device according to claim 10, including three control grids and means for applying positive voltage pulses simultaneously to two of said control grids and means for applying a negative voltage pulse to the other control grid.

12. An alternating current amplifier comprising a gaseous discharge tube having an envelope enclosing an anode and a cathode, a direct voltage source connected between the anode and the cathode, an alternating voltage source, control means connected to said alternating source for varying the discharge current through said tube in accordance with the voltage of said alternating voltage source, said control means comprising a perforated grid electrode connected to said alternating voltage source and interposed between the anode and the cathodeand substantially separating the anode from the cathode, the size of the perforations in said grid electrode being smaller than the mean free path of the electrons and ions in said tube, and means for biasing the grid electrode with respect to the cathode with a voltage which causes extinction of the gas discharge.

13. An alternating current amplifier according to claim 12, wherein said biasing means includes switching means for applying one biasing voltageto said grid electrode for igniting a gaseous discharge in said tube and for applying a second biasing voltage to said grid electrode for extinguishing the gaseous discharge, said biasing voltages being less than the anode to cathode voltage.

14. An arrangement for initiating and extinguishing an electronic plasma-type glow discharge in a gas filled electron tube, comprising a gas filled tube having an envelope enclosing a cold cathode, an anode and a control grid between the cathode and anode, said grid having perforations of a size which is smaller than the mean free path or the electrons, means for applying a positive bias potential to the grid relative to the cathode of the magnitude of the plasma potentiahmeans for applying a direct voltage between the anode and the cathode, means for applying a variable control voltage between the control grid and the cathode, said variable control voltage being of a sufiicient magnitude to initiate the glow discharge in said tube when the plasma potential is exceeded and extinguish the glow discharge when the control grid voltage drops below the plasma potential.

15. An arrangement according to claim 14, wherein said tube includes a plurality of control grids and wherein said means for initiating and extinguishing'the glow discharge applies a direct voltage to. one grid and said variable voltage to at least one other ofsaid plurality of control grids.

References Cited in the file of patent UNITED STATES PATENTS 1,145,735 Ainsworth' July 6, 1915 1,789,626 Hendry Ian. 20, 1931 1,937,389 Langer Nov. 28, 1933 2,077,288 Ardenne Apr. 13, 1937 2,292,382 Le Van Aug. 11, 1942 2,443,205 Stutsman- June 15, 1948 2,468,417 Stutsman Apr. 26, 1949 2,616,986 Coleman Nov. 4, 1952

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