US2474224A - Electronic switch - Google Patents

Description

June 28, 194%.

T. H. CLARK 2,474,224

ELECTRONIC SWITCH Filed March 20, 1947 3 Sheets-Sheet l ammo/MM TAEVO'? H. C AKK June 28,1949. H, ARK 2,474,224

ELECTRONIC SWITCH Filed March 20, 1947 5 Sheets-Sheet 2 3 it: s 6

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June 28, 1949.

Filed March 20, 1947 H. CLARK ELECTRONIC SWITCH 3 Sheets-Sheet 3 12, 15 M I?! gwvvwtm 779670 h. CLARK Patented June 28, 1949 ELECTRONIC SWITCH Trevor H. Clark, Boonton, N. J assignor to International Standard El York, N. Y., a corpora Application March 20 In France Section 1, Public Law Patent expires 7 Claims.

The invention relates to improvements, modifications and additions to the devices and circuits described in my copending application, Serial Number 735,953, filed March 20, 1947.

In this copending application were described electron discharge devices in which the electronic flux assembled in an electron beam was deflected in order to strike at difierent points of a collecting structure, with suitable focussing at each point of impact.

These arrangements in particular employed structures for the concentration of the electronic flux, consisting of two parallel plates in the form of the arcs of coaxial cylinders between which the said electron flux was transmitted, and the deviation of the electronic beam was ensured in certain embodiments by the variation of the potential of one of these plates, preferably the plate with the greatest radius.

It is one of the objects of the present addition to provide improved devices employing such a structure of concentrating and deviating electrodes.

The copending application mentioned above also described the means for controlling the deflection of the electronic beam of such tubes, particularly by means of electrical current impulse transformer, into deflection control potentials.

It is another object of the invention to provide improved control circuits for certain structures described in said patent application and for the structures described in the present invention.

The invention will be explained in detail in the following description given in relation to the attached drawings in which:

Fig. 1 represents an electron discharge structure similar to that shown in Fig. 3 of the above mentioned copending application.

Fig. 2 represents a circuit incorporating characteristics of the present invention, to control the operation of the device of Fig. 1;

Fig. 3 represents a modification in accordance with certain characteristics of the present invention, of the structure in Fig. 1, or more generally, of any one of the electron discharge device structures provided in the copending application.

Figs. 4 and 5 show curves employed in the explanation in relation to this modification of structure; and,

Fig. 6 represents another example of a circuit more particularly arranged to be used to control the operation of an electron discharge device structure incorporating characteristics of the present invention.

ectric Corporation, New tion of Delaware 1947, Serial No. 735,954 April 28, 1939 690, August 8, 1946 April 28, 1959 Referring first of all to Fig. 1, the embodiment of an electron discharge device shown comprises a cathode l, of which one surface only is active on account of the presence of the electrode 2 which is maintained in the vicinity of the potential of the cathode I, or at the same potential. This electrode consists of a cylinder of the same axis as a longitudinal axis of the cathode having an elongated opening in front of the surface of the cathode, of which the emission is to be utilised. Concentric with this electrode is another cylindrical electrode 3, having an opening aligned with the opening of the electrode 2, and brought to a suitable potential in order to accelerate the electrons emitted. Two concentric cylindrical plates 4 and 5 are arranged so that the electronic flux from the cathode l passes between them the axis of the structure generating the electronic flux being midway between the two plates 4 and 5. These plates are extended on a length of arc of about 127 in order to obtain the desired effect of concentration of the electronic flux coming from the structure generating and accelerating electrons on one of the collecting electrodes to, 6b, 6c. The plate 4 is kept at a positive potential with respect to the cathode, and the plate 5 at a negative potential or slightly positive potential with respect to the cathode, which ensures an eifective concentration of the electronic beam on the plate 6.

In this structure, as described in more detail in the above named application, in order to vary the position of the beam from one collecting electrode to another, it is possible to vary the potential of the electrode 5 by applying to this electrode a potential derived from the control potential or the electric control impulses. The circuits which will be described in the following will employ this electrode 5 as variable electrode, although an additional electrode may be provided for this purpose. Nevertheless the structural modification of the device itself forming a part of the present invention, is only of particular interest for the devices in which the electrode 5 is employed as radial deflection electrode of the electronic beam. Moreover, although this modification of structure is described in the present specification in relation to the structure of Fig. 1, it is clear that it is not limited thereto but may obviously be applied to described in my copending ap prising the use of the electrode corresponding electrode as electrode.

A method of operation of an electron discharge lication and com- 5 or of the special radial deflection device with radial deflection such as that shown in Fig. 1, will first of all be described with reference to Fig. 2 which represents a circuit for control by electricalimpulses "of aJdBViCi-l fof hthiS kind in accordance with certain' -characteristics of the invention. The control system of this kind, by electrical impulses transformed into electrical potentials determined on a deflecting electrode may be employed in telegraph'or 'telephone systems, remote control ,or indicating. systerns, etc., the number of-collector elements :6 of the structure being adapted to bemodified as desired and provided in order to fulfill the particular requirements of the system in which the device is employed.

An impulse dial 1, the details ofiwhich are not shown and which may consist of any suitable impulse transmitting dial, for example a dial with normally open impulse contacts, is connected by the line 8 to an impulse repeating relay 9 by a seriescircuit comprising the battery l9 connected to-earth,-one' winding-*ofthe relay 9,one-wire of the line-8, the-impulse transmitting contacts "of the *dial'! ('not shown) ,the other wire of'theline 8,-'the other winding of" the relayfi; and earth.

"The-relay-9is*provided with'a set of contacts comprising an armature HJ "associated with a back contact H and'a frontcontact 12. When no impulse "issent from the impulse diall, the armature F 'is'on the contact H andthe condenser fFis-charged'throughthe resistance M by the battery l3. When an impulse' is f transmitted the relay '9 is *energisediits "armature comes into engagement with the 'contact 12, and the-condenser -l" "is connected through the resistance l 4 and the contact i 2 in parallel withthe' high-capacity condenser -lfito'the plate "of thegas discharge device l"|,-which=fcr example, mayconsist of 1a gastriode'of-the well-known type, of which thegrid is polarised 'by'a-battery l8, and to "the deflecting electrode '5'itowhichlit-applies .a potential whichcauses"theidisplacement-of the electronic beam 'of the "device :for :radial deflection fromthe'position'it occupies to an adjacentposition, for example causes t e displacement of the beam from the electrode 13a to the electrode" Bb.

{In the embodiments shown the electrodejiz 'of the electron'disch'argedevice is shown grounded together-with the cathode, while the accelerating electrode 3 *isconnected to'the low'potentialBT and the -'collecting electrodes to the' 'high potential HT through the measuring apparatus Ia, Tb, Ic, source HT being also 'connected to the electrode '4of the device.

Assuming thatthe normal position of the electronic beam or the discharge device is on the electrode fiawhen-a firstimpulseis sentfrom the dial, the circuit of 'there'lays is closed by the contacts of the 'dial (not shown) and the relay operates, attracting its armature to the work contact l2. The condenser which .had .been charged by the battery 13 by means of the contact l-I, and'which-moreover*hasbeen chosen of such value in relationto the resistance 14, that ithasbeencharged in a pra-ctically instantaneous manner by the battery "1 3 is'now connected-tmthe electrode 5 of :theelectron discharge device and to the'con-d'enser i6 and the gas discharge device "Fl in parallel. :It "consequently applies .a fixed *potential to {the electrode 5, which ensures .a deviation oft'he 'electronic'beam of the electronic discharge device'frorn thecollecting electrode 6a to the collecting electrode 5b. It will remain there on account of the charge of the condenser Hi under the 'action of the condenserl'S oncethe condenser l5 has returned to position of charging by the battery at the time of the retraction of the armature H] on the contact II on account of thee de-energisation .of r the relay 9 by iopening of .the circuit #:ofithis relay ..on aeth'e -contacts (not shown) of the dial. The condenser l6, under the effect of the charge of the condenser l5, takes a charge which is not suflicient to afiect the ionisation of the gas discharge device I! as a result .of .suitable adjustment of the grid bias applied =to=the grid of the-latter by the battery 18.

Upon occurrence 'of the second impulse sent by the operation of the dial 1, the same opera- *tion willtakeplace and the beam will be directed,

under the action of the potential applied to the electrode ivso as to fall on the collecting elec- -trode-?6c,-'since this potential will result from the two successive charges brought by the condenser f5 tothe condenser l6, which cannot again be discharged through the device l1 in parallel.

Upon the-thirti'impulse sentby the-dial 'z'l 'the relay 9" will operate, but then'the contribution of the charge of the condenser I 5 on the condenser IE will give'the latter such a-difierence'of potential on *the terminals that it :will overcome-the polarisation potential of the discharge device I] and will effect the ionisation of "the latter. The condenser W6 will be discharged through 'the idevice H, -and==consequently no potential willeany longer be applied to the eIectrodes S'andthe beam will return to 'normalposition -on the collecting electrode 6a.

In one embodiment thegas discharge device consisted -'of --a mercury, argonyneon, or other gas-vapor relay, "of *whi'ch the battery potential F8 was adjusted so that the relay be'came conductive when the potential 'applied to the condenser i6 exceeded- 90 -vo1ts,'inorder to discharge the condenser 16. The plate'b was at-a 'zero'potentialin-order that the "beam might fall on the collecting electrode 6a, at a positive 1 potential of 50 'volts in order that the -beam might f allon the collecting electrode 6b, and of plus volts inor- 'der that the beam might f all -on the :collecting electrode bc. 7

'Applicant has' 'however' 'found that during the operation'described, "and which *may be ge'n'eralised forall the 'structures fthe application referred to above, the current on the electrode?! was not zero and 'the -=result *was' that the condenser I -6 did not strictly retain its charge,=but was charged or -discharged according to the direction "of the "current on the plate "5. The current inthis circuit consisted in thefirst place of primary electron-s coming from the electronic flux of the cathode I of the valve, and in the second place of secondary electrons coming from the'plate 5,collec' te'd by -the plate *L Whih is at a higher positivepotential.

=C0ns'equ'ent1y, *the invention also supplies means and structures of electrondischarge devices in order to eliminate 'theseparasitic'currents in the plate 5 and consequently to increase the stability and good operation of these devices.

Generally --speaking, the modification 'of'th'e structures with radial deflection provided in the present invention, consists in the realization'of structures in which the radial deflection electrode is removed 'from the position which it occupied in the structures of .the above named application, by 'such a displacement, *andbrought to such a "constantlyfnegaitive :or' 'zero fpotential with respect to the cathode that all variations of potential on thiselectrode areiin the inverse sense of the potential variation producedthereon in previous control systems of radial deflection tubes.

It is, in effect, known that in a co-cylindrical structure the distribution of potential may be expressed by:

log in which relation ET represents the potential along a cylinder of any radius r comprised between the two extreme radii R1 and R2 of the structure, E1 representing the potential of the electrode of radius R1. These notations will be more clearly understood with reference to Fig. 3, which shows such a co-cylindrical structure as that used in a device of the present invention in order to concentrate and deflect the electronic beam.

The variation AEr of the potential at one point of radius r in terms of the variation of potential AE2 along the cylinder of radius R2 may be expressed as follows:

It Will be seen that AET is a linear function of AEz if the dimensions of the structure are maintained constant.

In Fig. 4 the ratio of the variations of potential AE. AE

in ordinates is represented in terms of the ratio RZ/Rl in abscissae, for diiierent values of the ratio r/Rr. It will be seen from these curves that it is possible to give the plate 5 a greater radius in the electrode structure 4-5 and a slight change of potential of the plate 5 only is sufficient to obtain the same deflection of the beam. For example, referring to Fig. 4, the variation AEr is 75% of A182 when R1. is equal to 7.5; r to 19.5; and R2 to 27.

In Fig. 5, the values of R2 in mm. are plotted in ordinates in terms of the values of R1 in mm. for two different values of the ratio with a difference of radii rR1 constant. It will be seen that for each ratio there is an optimum value of R1 which gives a minimum value for R2. Such curves might be traced for any desired value of the ratio. The existences of a minimum value of R2 is important in order to obtain tubes of small dimensions.

Consequently, in order to avoid the drawback mentioned above, of the passage of current in the plate electrode 5, this electrode is taken of a greater radius than the normal radius for which the generator structure of the beam had its axis A coinciding with the aXis of the cylindrical structure of the plate electrode, but it will be then brought to a potential defined by the above curves in order to create in its original position a potential surface of the same value as in the case in which it was provided at this position, the axis A remaining in its original position.

In its new position the electrode 5 is always at a zero or negative value with respect to the potential of the cathode, and consequently can never receive current from the cathode while ensuring a correct concentration of the electronic beam on the collecting electrodes 6a, 62), 60. The result is that the condenser I6 will not be charged or discharged by an interference ourrent in the electrode 5, but will remain at a constant charge value, and that the deflection f the beam will not vary in time once determined by the impulses coming from the transmitting dial 1.

It should be understood that this modification of structure is not limited to the tube structure of Fig. 1, but can, on the contrary, be employed with advantage in all electron discharge devices considered in the copending application, and, generally speaking, in all electron discharge devices employing a pair of parallel electrodes for the concentration of the electronic beam in which the potential of one electrode is modified in order to ensure stable deflection of the beam.

Fig. 6 shows an example of a control circuit of a modified discharge device in accordance with characteristics of the invention, this circuit being able to be employed, preferably instead of the circuit of Fig. 2, for the control of these tubes.

This circuit is relatively similar to that of Fig. 2, but now it is the positive terminal of the com denser I5 which is earthed and the negative tor-- minal on the new electrode 5 of the electron discharge device, in which the original position of the electrode 5 has been indicated in broken lines. The dimensions and the potentials applied to the electrodes 4 and 6 of the electron discharge device are chosen so that the potential along the surface indicated by broken lines is approximately positive by volts with respect to the cathode I when the potential on the terminals of the condenser I6 is zero. This value, moreover, may be different from 80 positive volts, according to the case, and should simply corre spond to the value for which the electronic beam is attracted to the collecting electrode 60 when the circuit is at normal. The operation of the circuit will then be similar to that of Fig. 2, with the exception that after the first impulse the electrode? will be negative with respect to the cathode, consequently the potential along the surface indicated in broken lines will be less positive with respect to the cathode and the beam will be brought on to the electrode 61). In the same way, the second impulse will bring the beam on to the electrode 6a, and the third, discharging the condenser l5, through the gas discharge tube [7, will cause the electronic beam to return to the electrode 60.

This method of control of the device with radial deflection may also be employed for any device with radial deflection and not merely for that device shown diagrammatically in Fig. 6.

Other modifications and adaptations may be employed without departing from the scope of the invention.

I claim:

1. A system for electronic switching, comprising electron beam switching means including a pair of deflecting electrodes and a plurality of target anodes disposed therebetween, one of said electrodes normally being kept at a fixed potential and the other electrode being at a distance from said one electrode such that its potential with respect thereto is of a value as to at least inhibit current flow therein due to attraction of any of the electron emission of said switching means and due to secondary electrons attracted from said other electrode to said one electrode, and means for supplying voltage impulses to said other electrode including means for additively storing said voltage impulses, whereby the potential of said other electrode is successively varied 7 to effect ardefiection of the electron toward target anodes -rsubstantiaily adjacent to said other electrode.

2. :A system according to claim 51, wherein said voltage impulse supplying means further includes a zmaintand saniauxilianyipotential storage device having zeachjaa. positive'and :a :negative terminal, said negative teim'iina-ls being connected to said other electrodaiand .relay means for discharging said main storage device upon attainment thereon-of "a given potential.

'3. Inc-an 'electronic switching system, in combination, an electron-emitting cathode, focusing means forthe electronscmitted by said cathode, saidiocusing means including a first and a second deflecting electrode between them defining apathfor said ielectrons, raplurality of target electrodes positioned in said path, output means connected to :certain df'said electrodes, circuit means ':for mainteining said target electrodes and said first deflecting electrode at a positive potential relaaative to said cathode, and input means 'aldaptedtoeapply axplura'lity of different deflectinggmtefitials to said :second deflecting electrode, the m'o'st zpos'itive -rof :said deflecting potentials-being not moremositive than the potezitial of said :rcathode.

14. The combination according to claim '3 wherein sa'id deilecting #electrodes are a pair of 'coimial cyImiier'iseQments'said cathode *beingd ocated-oloser tomaid firstthan to said secdflecting electrode.

5. "The' combmatlomaccord-ing to claim 4 wherein th'e radius ofa'saii'd first deflecting electrode is less 'than the radius (if said second deflecting electrode.

#6. ln an electronic switching system, in combina'tion, *an electronertii-tting cathode, focusing adapted to-apply a plurality of different deflecting I potentials to the outer one-of said deflecting electrodes, said input means including a gas :discharge tube having a variable-voltage electrode connected to said-outer deflecting electrode, the potential on saidvelriaLble-voltage electrode being arranged to'vary b'etween an ionization potential 'and'an extinction potential the more positive of which-is not more positive than the potential of said cathode.

'7. The combination according to cl-aim'6'wherein said gas discharge tube "has a cathode representing said variable-voltage electrode.

TREVOR H. CLARK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,955,332 Iams Apr. 17, .1934 2,114,016 Dimond Apr. '12, 1938 2,224,677 Hanscom Dec. 10, 1940 2,275,460 Page Mar. 10, 1942 2,301,197 Bradford Nov. 1'0,-19&2 2,380,225 Fleming-Williams July 10, 1945 2,411,648 Brauer etal Nov. 26,1946

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