US2204055A - Telephone system - Google Patents

Description

June l1, 1940. A. M. sKELLErT TELEPHONE SYSTEM Filed Nov. 25, 1958 5 Sheets-Sheet 1 2"D GROUP sus 5/ Il .Insul- 2, ZTL

A. M. SKELLETT /N VEN TOR ATTORNEY June 11, 1940. A. M. sKELLETT 2,204,055

TELEPHONE SYSTEM Fld NOV. 25, 1938 I5 Sheets-Sheet 2 mvg/v70@ A. M. SKELLETT A 7' TURA/Ey June Il, 1940. A. M .sKELLETT 2,204,055

TELEPHONE SYSTEM Filed Nov. 25, 1938 I5 Sheets-Sheet Z5 SEL.

T0 NEXT FINDER /Nl/ENTOR AM. SKEL/ ETT A TTORNE V Patented June 11, 1940 UNITED STATES PATENT OFFICE TELEPHONE SYSTEM Alberi ri. sirene,

Madison, N. J., assignor to Bell Telephone Laboratories,

Incorporated,

14 Claims. This invention relates to telephone systems and particularly to improvements in automatic controlling the establishing of connections inl such systems, and particularly to the elimination of some of the individual equipments usually provided for subscribers' lines.

Heretofore in automatic telephone systems, various arrangements have been provided whereby when a subscriber calls, an individual line relay is operated to cause common mechanisms and circuits to seize an idle line finder and cause it to operate to find the calling line and connect it to succeeding switches for the extension of a connection. Usually the line relay operates a common start relay for this purpose. Systems have also been provided whereby such individual line relays have been eliminated by relay mechanisms or other devices such as vacuum tubes common to a plurality of lines.

It is a feature of the present invention to provide a common mechanism for one or more groups of calling subscribers line circuits for the operation of start relays individual to such groups of lines for starting control operations to connect thecalling line to an idle line finder. This common mechanism may consist of a plurality of coils, one for each line wound on a common core and a cathode ray tube and circuit means whereby an electron beam in said tube may be deflected by the energization of any one of said coils when the corresponding subscriber is calling to cause said beam to operate a particular common start relay.

Another feature is the provision of means for preventing the straying of the beam from a neutral position to cause false operation of a 40 common start relay due to leakage conditions on the lines. Deflection plates are employed for this purpose and circuit means are" operated by the beam `and caused to control the potentials on said plates to return the beam to its neutral position. l n

A special feature relates to the arrangement of the coils on the core. The coils may, for example, be divided in two groups and so7 connected that one group produces iiux` in one direction across the air-gap of the core and the other group produces flux in the opposite direction across this air-gap. This requires the tube to be equipped with two anode plates so that the energization of any one of one group of coils will deflect the beam to one anode and (ci. 11s- 13) the energization of any one of the coils in the other group will deflect the beam to the other anode. If the tube is arranged in this manner. one anode circuit may control one-start relay for one group of lines and the other anode cirv cuit may control another start relay for another group of lines. l

A modified form of the invention may be an arrangement whereby a gas-filled tube isl controlled by the flux of a permanent magnet core 10 which prevents the tube from operating normally and whereby when any one of the coils on this magnet core is energized the tube is caused to operate to close the circuit for the start relay. This modification of the invention may be so arranged that a cathode ray tube is used in place of the gas-filled tube in which case the permanent magnet defiects the beam away from a single anode and whena coil is energized the beam is deflected to strike this anode to close the circuit for the start relay.

A modified form of the feature relating to the balancing out of leakage effects may be employed in connection with the above modifications and take the form of a special coil in series with a line' coil. 'I'his special coil may be distributed over the entire permanent magnet core and wound to produce flux in the opposite direction to the flux produced by the line coil to counteract leakagev currents. 30

The invention has been illustrated in the accompanying drawings in which:

Fig. V1 shows a preferred form of applicants invention applied to a telephone system;

Fig. 2 shows in perspective the cathode beam tube, core and coils used in Fig. 1;

Fig. 3 shows a modified form of the applicants invention in which a gas-filled tube and a permanent magnet core are substituted in place of the cathode beam tube and core in Figs. 1 and 2; this figure also shows a modification of the applicants invention of the feature relating to the balancing out of the leakage effect; and

Fig. 4 shows a modified form of the applicants invention in which a cathode beam tube is 45 substituted for the gas-filled tube shown in Fig. 3.

Fig. 5 shows' a typical line-finder circuit in detail for seizing a calling line arranged in accordance with the applicants invention when 50 applied to a telephone system as illustrated diagrammatically in Figs 1 and 3.

Referring now to Figs. l and 2, a cathode ray tube I may contain the usual beam producing ,element or cathode 2, a pair of deiiecting plates 8 and 8, a usual high potential screen 8 and the anode plates 8 and l. The core 8 is located in. relation to the cathode beam and the deflection plates l and 8 as shown in Fig. 2 so that the magnetic lines of force passing across the airgap I between the poles of this core are at right angles to the deflection plates l and l. As is well known in cathode beam tubes of this type, the beam will be deected. referring to the picture of the tube in Fig. 1, to the right or to the left to strike the anode 8 or 'I by the` magnetic lines of force passing between, across the air-gap I8 and varying potentials on the deflection plates 8 and 8 will deflect the cathode beam in the same directions. Nbrmally the beam is not deflected but extends in a neutral position directly through the center of the tube to pass between the anodes 8 and l. In other words, with the deflection plates and the magnet core placed as shown in these figures, the electrostatic and magnetic deflections are effective in the same direction. The direction of deflection of the beam depends in the case oi' the magnetic deflection on the polarity of the magnetic field and is perpendicular to the field, and the electrostatic deflection, the amount of which is proportional to the potential defierence between the deflecting plates, is in a direction toward the plate of the higher potential. In Fig. i the magnetic core 8 has been pictured above the tube I for the sake of clearness but it should be understood that this core is placed in relation to the tube as shown in Fig. 2.

On core 8 may be placed individual coils of individual lines and these may be divided in groups In Fig. 1 the coils of six lines have been shown, three'of each of two groups which may be representative of lines of two groups of ilfty each. 0f the upper group of subscribers' lines. I, 2 and III have been shown and in the lower group of subscribers lines, 8|, 88 and |88 have been shown with their respective coils on the core 8. 'Ihe coil I-A of line I, is connected in a circuit from battery through this coil. contacts of the cut-of! relay II, the subscribers loop and contacts of relay II to ground. Next to this coil I-A has been Placed coil 8I-A of line 8I in a circuit from battery through this coil, contacts of the cut-ofi relay I2 of line 8|, the subscribers loop. contacts of relay I2 to ground. The succeeding coils of the succeeding lines are placed on the core 8 alternately, that is, the next coil after II-A will be the coil 2-A of line 2 and the last three coils 98A, 88-A and Ill-A on core 8 are those of lines 88, 88 and I 88. It should be noted that the coils of lines Ito I8 are wound on core 8 in the opposite direction to the coils of lines 8| to IIIl so that when a coil in the first group is energized. the magnetic lines of force across air-gap I8 will be in one direction and when a coil in the other group is energized, the magnetic lines of force across air-gap I8 will bek in the opposite direction. 'I'hus when any of the coils in the first group are energized, the beam will be deflected towards the right and when a coil in the second group is energized, the beams will be deflected toward the left, to cause secondary electron emissions to be produced between anode 8 or 'I and the screen 8. These secondary electrons cause potentials to be established on the control element I8 or Il of the gas-filled tube I8 or I'I to cause either of these tubes to discharge, as will be explained hereinafter, and operate relay I8 or I8, to close circuits for the operation of the start relay 28 or 2l. As shown, the subscribers lines in these two groups are connected to the terminals o! lineflnder switches at 28 to extend connections from the subscribers lines as is well known in the art and described hereinafter in connection with Fig. 5. To start the establishing of such connections, the start relay 28 is provided for the first group of subscribers lines and the start relay 2I is provided for the second group of lines.

The operation of this system is as follows: If it is assumed that the subscriber I in the first group calls by removing his receiver from the switchhook, a circuit is completed from battery, winding I-A, contacts of the relay I I, the subscribers loop, contacts of relay II to ground. 'Ihis energizes core 8 to produce electromagnetic lines of force across air-gap I8 to deflect the beam of tube I to strike anode 6. This establishes a conducting path between anode 8 and screen 8 and thus the potential as determined by the high potential battery I3, this conductive path between anode 8 and screen is established on the control electrode I8 of tube I8 through the resistance 21. As this potential is more positive than the potential on the cathode 28 as determined by the battery 29 the tube breaks down. 'Iube I8 now discharges between the cathode 28 to the main anode III, and a circuit established for the operation of relay I8 from the positive pole of the high potential battery 3i through contacts of the cut-0H relays of the subscribers of the ilrst group such as 82 of line 50, 33 of line 2 and I I of line I, winding of relay i8, main anode 88, cathode 28 to the positive pole of the lower voltage battery 28 to ground. Relay I8 in operating closes an obvious circuit for the operation of relay 2l which now serves to start operations, as will be hereinafter described in connection with Fig. 5, towards the seizing of the calling subscribers line I by an idle line finder to extend the subscribers line to switches of any well-known automatic system for the establishing of a connection to a called subscribers line. When the connection is extended through a line finder for subscriber I, cut-oi! relay II will' operate in the usual manner and release the relay I8, extinguish tube I8 and deenergize coil I-A oi.' core 8, and the beam is thus rapidly returned to the normal or neutral position. However, the circuit for relay I8 is again closed on the full operation of relay I I to permit any other subscriber to call while subscriber I is engaged. Thus the momentary opening of the circuit for relay I8 permits relay 2li to deenergize. In a similar manner any other subscriber of the first group may by removing his receiver from the switchhook cause the corresponding coil on core 8 to be energized to deflect the beam on anode 8 and reoperate relays I8 and 2l.

If a subscriber in the second group has called, for example subscriber 5I, the circuit for coil .5I- A on core 8 would have energized over a circuit from battery, winding of this coil, contactsv of cut-oir relay I2, the subscribers loop, contacts of cut-oil' relay I2 to ground and thus cause the beam to be deflected to anode 1. I'his would have established a potential on the control electrode I8 of tube I1 to cause this tube to discharge over a circuit from the positive pole of the high potential battery 88, contacts of the cut-ofi' relays of all the subscribers in the second group, such as l0 of subscriber |88, 4I of subscriber 88 and I2 of subscriber 8l, winding of relay I8; main anode l2 and cathode 43 of tube I1 to the positive pole of a lower voltage battery u. Relay I8 in operating subscriber I through' an idle line finder for the -extension of a connection. If the calling sub- 'resistance |08, condenser 55 leakage occurs on any of scribers line 5I is extended to the line iinder, the

cut-oi relay I2 operates and releases relays I8 and 2| and causes tube I1 to cease discharging and they beam is returned tor normal.

As stated. the beam in tube I is normally pointed at a position between the two anodes 8 and 1 and to prevent the beam from wandering of! this neutral position to cause false operation of a. start relay, feedback circuits are provided. It should be observed here that these feedback circuits are not effective in this respect when a subscriber calls. That is, they are too slow ln operating during the extremely short period the beam is deflected by the energization of a coil, this being due to the characteristics of resistance IIiI, for example, in case the beam is deflected on anode 8, and as due to the characteristics of resistance |08 in case thebeam is deflected on anode 1. The feedback circuits are connected, respectively, from the anodes 6 and 1, through resistances IDU and IIlI, to the deilecting plates 3 and 4, and the circuit for anode 8 is aso connected through the resistance IIII, condenser` 52 and'resistance 53 in parallel .to battery 54, while the circuit for anode 1 is also connected through and resistance J8 in parallel to a battery 51. The wandering of the beam from neutral position may be caused by leakage currents on the subscribers lines. through the coils around the case 8 which would cause corresponding coils to be partially ener-.

gized. If such leakages occur and remain for any length` of time, a potential difference is established between the-deec`ting plates 3 and 4 to cause the beam to be returned to the neutral position. That is to say, for example` if the the lines in the first group, a corresponding coil of this group on core 8 will deflect the beam towards anode 8. This will through resistance IIJI cause an increase of potential to be established on plate 4 which will draw the beam back to the neutral position. The nature of the leakage is generally such that it will cause the beam to be deflected so that only a part of it will strike anode Bor 1. The secondary emissions between either of these plates and the screen 5 will therefore not be sufficient to cause the corresponding tube I8 or I1 to discharge. On the other hand the feedback circuit will become effective due to such emissions as, for example, if the beam is partially deflectedA to strike` anode 8, the condenser 52 will have sufiicient time to receive a charge as determined by the values of resistances IUI and 53- and thus increase thepotential on plate 4 which, in turn, causes the beam to be returned towards the normal position. Itis evident that this effect can not be produced when the beam is fully denected on theanode 6 when a line is closed, as in this case tube I8 will dischargeimmediately due to the potential drop across resistance IDI, and in this case plate 4 will not have time to change its potential as the beam will be almost immediately deflected back\ to normal position by the operation of a cut-oil relay which, as stated, deenergizes the associated coil on the core 8. To recapitulate, the potential of defiecting plates 3 and 4 cannot be changed rapidly because of the relatively longr time constants of the combinations of condenser' and resistance 52, 53 and 55, 58 connected to them. Thus they are effective in returning the beam to its neutral position only for slow variations of flux, such as are produced by leakage currents in the subscribers lines.

Referring now to Fig. 3 which shows the ap.- plicants idea modified to employ a gas-filled tube 8D having an electron emitting element 8I and anode 82 and a screen 83, a permanent magnet core 84 is placed in proximity to this tube so that magnetic flux across its air-gap passes between the element 8I and the screen 83 to normally prevent electrons from passing to 'the anode 82. On this core are wound individual windings of, for example, fifty lines, three of which have been Ashown extending to subscribers stations 85, 66

and 81,"respectively.

This device operates as follows: If, for example, the subscriber at 85 removes his receiver from the switchhook, a circuit is completed for the corresponding coil 88 on the core 84 from thel positive pole of the high voltage battery 10, three auxiliary windings 1I, `12 and 13 wound in a direction opposite to winding 88 and opposite to all other line windings on core 84, resistance 14, and across the condenser 15 in parallel ofwindings 1I, 12 and 13 and resistance 14, winding 68, contacts of the cut-off relay 18 through the subscribers loop of line 65, contacts of cut-off relay 16 to ground. The sudden flow of current through this circuit rcharges the condenser 15 before coils 1|,.12 and 13 receive suflicient cure rent to produce any effective flux in the permanent magnet core. The purpose of coils 1I, 12 and 18, and resistance 14 is to restore the tube to normal condition and to counteract leakage effects 'and their functions in those respects will be explained hereinafter. The immediate eiect of the current in this circuit therefore is that winding 68 becomes energized and the flux produced thereby in the core 84 will be in opposition to the normal flux Aacross the air-gap of the core 84 and thus permits the tube to operate to permit electrons from the element 8l to pass through plate 83 to anode 62. This provides a path for the operation of relay 18 from the positive pole of the high Voltage battery 19, contacts of all the cut-off relays such as 80 of the line 81, 8l of line 88 and 18 of line 85, winding of relay 1S, anode 82, cathode 8l to ground. Relay 18 operates in this circuit and closes an obvious circuit for the start relay 83 which causes an idle line finder to seize line 85 and extend it beyond for further Iautomatic extension. When a line iinder hasl seized this line, the cut-off relay 18 'counteract the flux produced by winding 58 and hence permit the flux produced by the permanent magnetism in the core to soon prevent electrons from passing through from the element 8l to anode 82 and thus blocking any further current through re'ay 18. These coils are also effective to restore the tube to a condition where energize.- tion of any line winding will become ineffective until the circuit of relay 18 has operated when any other subscriber removing his receiver from his switchhook will cause the circuits tooperate to extend a connection in the same manner as described in connection with a call from subscriber of line 85.

As stated, to overcome leakage current effects in this arrangement, the auxiliary windings 1I, 12, and 13 and resistance 14 are provided in series with line windings over the circuit as hereinbefore traced for the nrst line through the line winding Il. Itshould be noted that these auxiliary coils may be distributed over the entire core or in sections and, as stated, are wound in opposite directions to the line windings. Their functions in regard to counteracting any leakage currents that may exist in any one of the lines are as follows: As leakage currents in the lines are oflow values, the coils 1|, l2 and 12 become eflective on such leakage currents to balance out the flux in any of the line windings through which leakage currents may pass. That is to say, if a small leak in current occurs in the line and as the resistance value of the resistance 'Il is comparatively small, the condenser 'Il will have a correspondingly small difference of potential across it, and hence the leakage current flowing through the windings 1|, 'l2 and 'I3 may be of the same value as the leakage current nowing through said line windings and its coil such as Il, and consequently no effective flux will be produced in the core Il.

Fig. 4 shows the arrangement in Fig. 3 modified to substitute a cathode ray tube 0l in place of the gas-filled vacuum tube 0l but otherwise functions the same with the exception that the core 5l need not be a permanent magnet as normally the beam does not fall on the anode Il. In this case, therefore, when s.'` line coil is energized, the flux produced by this coil in the core M causes the beam to be deflected onto the anode plate 0| and thereby closes a circuit for the relay 15 and start relay Il. When a current is built up in the coils 1|, 12 and 1I, the beam is restored to the normal position in the same manner as hereinbefore described in connection with Fig. 3 both in regard to the restoring after the energization of a line coil due to the seizure of the corresponding line or due to leakages.

A description will now be made of the function of a typical line-finder circuit such as is disclosed in Fig. 5 whereby a connection may be established from a calling line of the kind disclosed in Fig. 1 or 3 as embodying the applicants invention.

`Assuming as hereinbefore described that, for example, a relay such as 20 in Fig. 1 operates indicating that a subscriber in the associated group has initiated a call, it is evident that an idle line finder such as is disclosed in Fig. 5 will operate to seize the calling line and connect it through its line 'terminals through to a connection beyond. This line iinder disclosed in Fig. 5 is of the usual well-known type that operates in a vertical direction to advance its brushes, such as |00, to the level in the switch in which the calling line is located and to then advance the brushes in a rotary direction to connect the brushes with the terminals of a calling line. The testing for the calling line will be controlled primarily by a vacuum tube |02 and associated circuits 'over the ring terminal and the ring brush as will hereinafter bedescribed. A relay |0| corresponding to a relay such as relay 20 in Fig. i will operate when a subscriber initiates a call and the effect is that a start circuit is closed for the operation of a relay |02 over a circuit from battery. winding of this relay, the usual eleventh step contacts |04, contacts of relay |05 to ground at contacts of relay Ill. When relay |03 operates it opens a point in the circuit of release magnet |06 and places ground potential on the conductor |01. This prepares a locking circuit for relays |00 and |05 and operates the vertical magnet |08 over a circuit from battery, con# tacts of interrupter relay vH0, winding of m58-y erates and opens the circuit for magnet lill.y

Magnet |08 thereupon deenergizes and opens the circuit for relay 0 whereupon relay ||0 deenergizes and again closes the circuit for the magnet |00. This action continues until the circuit for this magnet is opened on the operation of relay |05 which takes place when the vertical magnet has advanced the vertical wiper lll to the third level of bank contacts. In this position the wiper is brought into engagement with the test contact 2. When this occurs a circuit is completedy for relay |00 from battery through its winding, wiper Ill, contact 2, contacts of relay |0| toground. Relay |00 in operating closes a locking circuit for itself through its inner lower armature and front contact to the ground at contacts of relay |03. Relay |00 also opens the circuit for the vertical magnet |09 and thereby terminates the vertical movement. Relay |0l now extends the ground connection from relay |03 to the rotary magnet H3 which operates over a circuit from battery, contacts of relay ||0, winding of magnet lll and contacts of relays |05, |00 and |03 to ground. 'I'he rotary magnet in operating closes a circuit for the operation of relay ||0 which opens the rotary magnet circuit so that this magnet releases and causes the release of relay |'|0. These actions are continued until the brushes |00 are opposite the terminals of the calling line.

It should be noted at this point that the grid of the tube |02 is connected to the ring brush ofl the line finder through a resistance ||5 and to a suitable` source of current ||6 through a resistance I1 and that the plate circuit extends through the upper winding of relay |05. Normally the potential on the grid of tube |02 is sufilciently negative to prevent the tube from operating. If it is then assumed that the subscriber No. 1 in Fig. 1, for example, is the calling subscriber, it should be noted that the source of current 92 is connected with its negative terminal to the ring terminal over the winding iA of the core 8 and contacts of the y cut-ofi' relay |I. Hence, when the ring brush of the-line finder finds this ring terminal of the calling line, the connection through the calling subscribers loop to ground over contacts of relay will change the normal grid potential to become sumciently less negative to cause the tube |02 to operate. The resulting current through the plate circuit will operate relay |05 and stop the line inder. That is, relay |05 in operating provides a locking circuit for itself through its lower winding and lower inner armature and front contact to ground at contacts of relay |03 and opens the circuit for the rotary magnet H3, so that the line finder will therefore remain connected to the calling line terminals. Relay |05 now ex-l tends the connection yfrom the calling line over the brushes |00 through contacts of the relay to a first selector for the establishing of a connection beyond, as is well known in the art. lRelay |05 also extends the starter wire from relayl 0| to the next finder. When ground is encountered over the sleeve conductor from the first selector, relay |20 operates from battery over an upper winding and provides a connection to grolmd for maintaining the relay I 03 operated after the starting' ground is removed by the operation ot relay |05. Relay |03 is slow in releasing so as to remain operated during this transfer of the connection. This ground connection of the sleeve from the ilrst selector also causes the operation of relay which disconnects, as hereinbefore described, the connection from the calling subscriber to a winding on core 0 and th/is in turn causes the tube |02 to be restored to normal and discontinue the current through the upper winding of relay |05.

The connection now established from the calling subscriber over the line ilnder. to the rst selector may now be extended to a called subscriber in they usual manner through any wellknown automatic telephone system by having the subscriber dial the called subscribers number. When the connection is released, ground is removed from the sleeve connection and thus causes the release of relays and |03 which in turn causes the -release of relays |00 and |05. 'I'he release of relay |03 closes the circuit for the, release magnet |06 from battery through the winding of this magnet, the vertical oil-normal con"- tacts |2| to ground. The release magnet restores the line finder to normal. It is evident that this relay |20 will not cause the release of the line finder if the starter Wire is used for operating another succeeding line finder at the time the circuit for the 'upper winding of relay |20 is opened as this relay |20 will be locked from battery through its lower winding to the starter wire ground. This locking circuit will, of course, be opened when the starter wire is no longer needed at which time the ground will be disconnected from this wire by the release of relay |0| which takes place when a line finder has found a calling line and the associated cut-0H relay is operated.

What is claimed is:

l. In combination, a plurality of lines, a coil for each line, a relay, a circuit for said relay, means for producing an electron beam, and means responsive to the energization of any one of said coils on the seizure of the corresponding line for controlling said electron beam to close said circuit t0 cause the operation of said relay.

2. In combination, a plurality of lines, a winding for each line, a core for said windings, a relay, a circuit for said relay, means for producing an electron beam, said core being so located in relation to theelectron beam that when flux is producedin said core by current in any one of said windings, said electron beam is iiexed from its normal direction, and means responsive to the lexing of said electron beam for closing said circuit to cause the operation of said relay.

3. In combination, a plurality of lines, means for transmitting current over any one of said lines, a relay, a circuit for said relay, a device for producing an electron beam, an electromagnetic core having its poles adjacent said electron beam for the deiiection of said beam by flux between said poles, windings on said core each connected to a different line, a terminal in said device connected to said circuit and so located that when current is passing through any one of said lines iiux produced in said core by the winding associated with said line flexes said beam to cause a current to flow over said beam through said circuit to operate said relay.

4. In combination, a device for producing an electron beam, an electromagnetic core having its poles in such. a position in relation to said electron beam that flux flowing between said poles causes said beam to be deilected, a terminal in said device, a relay, a circuit for said relay connected to said terminal. a plurality of windings on said core, means for energizing any one of said windings to produce ilux in said core to direct said beam on to said terminal to cause current to flow in said circuit to operate the relay.

5. In combination, a relay, a device for producing an `electron beam, an electromagnetic core arranged so that ilux between its poles will flex said beam, a plurality of windings on said core, means for energizing any one of said windings to produce flux between the poles of said core, means responsive to the iiexing of said beam by said ilux for operating said relay.

6. In combination, a device for producing an electron beam, two anodes in said device not in the path of said beam when inl a neutral position, a relay associated with each anode, means for deilecting saidV beam onto either anode, and means operative if the beam is deflected slowly onto either of said anodes for restoring it to the 4neutral position and operative if the beam is deilected quickly onto either of said anodes for actuating the corresponding relay.

7. In combination, a device for producing an electron beam, two anodes located in said device on opposite sides of said beam, a pair of ilexing plates for said beam in said device, circuit means electrically associating said plates and said anodes operative on the slow straying of said beam on to either of said anodes for restoring it to its neutral position between said anodes. 8. In combination, a device for producing an electron beam, two anodes located in said device on opposite sides of the beam when in a neutral position, a relay for each anode, a pair of iiexing plates for said beam in said device, circuit means electrically associating one anode with one'relay and a ilexing plate, circuit means electrically associating the other anode with-the other relay and the other ilexing plate, means for deecting said beam on to either of said anodes, said means being opera-tiveon the quick deiiectlon of said beam on to either anode for operating the corresponding relay and then restoring the beam vtoits normal position, and operative on the slow deflection Yof said beam on to either anode for restoring it to its neutral position without causing the operation of the corresponding relay.

9. In combination, a vdevice for producing an electron beam, two anodes, in said device within reach of said beam but not in the path of said beam when in a neutral position, a gas-lled tube for each anode, a relay for each tube in the plate circuit thereof, circuit means connecting one anode -with the filament of one tube and for connecting the other anode with the filament ofthe other tube, two groups of energizing windings, electromagnetic means controlledl by the .energization of any winding in one group for deilecting said beam on to=one anode and controlled by the energization of any Winding in the other group for deflecting said beam' on to the other anode for changing the potential on the control element of the associated tube to cause the operation of the relay in the plate circuit of said tube.

l0. In combination, a device for producing an electron beam, two anodes in said device within reach of said beam but not in the path of said beam when in a neutral position, a relay for each anode, an electromagnetic coil arranged so that flux between its poles will flex said beam, two

groups of energizing windings on said core, one u to produce flux in the opposite direction to ilex` group wound to energias said core to produce iiux in one direction to iiex the beam on to one anode and the other group wound to energize said core the beam on to the other anode. and means responsive to the change inthe electrical'characteristics of said anode when the beam is directed thereon at a slow rate for restoring said beam to its neutral position and when the beam is directed on said anode at a faster rate, tor causing the operation of the associated relay.

11. In combination, a relay, a device for producing an electron beam. an electromagnetic core arranged so that ilux between its poles will prevent said beam from being produced, a plu-` rality of windings on said core, means for energizing any one of said windings to produce nux between the poles of said core so as to permit said beam to be produced, means operative when said beam is produced for operating said relay, an auxiliary winding associated with all oi' said 'plurality of windings on said core, so wound that when any one of said wind.

ings is energized to a certain degree only, it produces an electromagnetic ilu`x in opposition toA the ilux produced by any one oi the said plurality of windings to neutralize said lastmentioned iiux in said core to duction ot said beam.

prevent the proyan electron beam, means for normally suppressr ing said beam, means responsive to the energize.-

tlon of any one of said coils for overcoming said suppression means to produce said beam, and means ,operative over said beam when produced for closing said circuit to operate said relay.

14. In combination, `a plurality ci lines, a coil `for each line, a relay, a device tor producing an electron beam, a permanent magnet core for said coils arranged in relation to said device so that normally magnetic lines of force suppress'v said beam and so that when am' one of said coils is energized, the normal magnetic lines oi' i'orce are counteracted by the magnetic lines of force produced by the energized coil vto permit the beam to be produced and means operative-gg over said beam when produced for operating said relay.

ALBERT MI. BKELLETT.

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