US2426188A

US2426188A - Automatic telecommunication system

Info

Publication number: US2426188A
Application number: US478695A
Authority: US
Inventors: Jean R A Escande
Original assignee: International Standard Electric Corp
Current assignee: International Standard Electric Corp
Priority date: 1941-10-31
Filing date: 1943-03-10
Publication date: 1947-08-26
Anticipated expiration: 1964-08-26

Description

Aug. 26, 1947. J. R. A. EscANDE 8 AUTOMATIC TELECQMMUNICATION SYSTEM Filed March 10, 194.3 '7 Sheets-Sheet 2 vi Q VB i Q g I INVENTOR.

. Jmzwiflfircmvai j BY ATTORMfY Aug. 26, 1947. J. R. A. ESCANDE 2,426,183

- I AUTOMATIC TELECOMMUNICATION SYSTEM Filed March 10, 1943 7 Sheets-Sheet 5 ATTORNEY 1947.- J. A. ESCANDE 2,426,188

AUTOMATIC TELECOMMUNICATION SYSTEM Filed March 10, 1943 '7 Sheets-Sheet 4 I N V EN TOR. Ji l/V I? [Saw/v05 I ATTORN J. R. A. ESCANDE 2,426,188 AUTOMATIC TELECOMMUNICATION SYSTEM Aug. 26, 1947.

Filed March 10, 1943 7 Sheets-Shagt 5 IN V EN TOR.

JFA/v IPA Esta/v05 ATTORNEY ooooooooooooooo El Aug. 1947- J. R. A. ESCANDE 2,426,188

I AUTOMATIC TELECOMMUNICATION SYSTEM Filed March 10, 194$ 7 Sheets-Sheet e Aug- 26, 1947- J. R. A. ESCANDE AUTOMATIC TELECOMMUNICATION SYSTEM Filed March 10, 1943 7 Sheets-Sheet 7 l||| In I lllllllllllllllllllllllllllll m 11 m kink fi m s s" n .m iJW ATTOR N Patented Aug. 26, 1947 AUTOMATIC TELECOMMUNICATION SYSTEM Jean R. A; Escande, Lyon,

France, assignor to International Standard Electric Corporation,

New York,

N. Y., a corporation of Delaware Application March 10, 1943, Serial Nb. 478,695 In France October 31, 1941 vertive impulses.

Another object of the invention is to eliminate arranged that whenever the selector leaves the terminals of a group oftrunks, an impulse is sent over the control circuit and the closure of' According to another feature of the invention, while the selector continues to hunt during the busy condition of all the trunks in the desired group, the" register relays will continue to receive impulses from the selector and insurethe continuance of the hunt.

An object of the invention is the provisionof a switching system in which revertiv'e or directive impulses maybe sent over the register control circuit." According to one featureof theinvention, selective impulses inay be received on a rotating element, such as a commutator, and the impulses controlling the setting of'the' selector are g 2 received until a p which have been marked by said element.

These and other features of the-invention-will be more fully explained in the following detailed description with the aidof the drawings in which: Fig. I is a schematic representation ofanautomatic system the circuits" of whichvembody the various features'of the invention; i f

F'ig.v 2 shows theconnection between the register and the control circuit; i a i" Fig. ,3 diagrammatically represents an' ernbodiment' ofthe invention in a groupselector;

Figs. 3a and 3b showthe control circuit for the selector and should be placedbelow one another and'below Fig. V

Fig. 3c shows a modification of Fig. 3a; and

Figs. 4, 4a and 4b; placed one below .th'eother, illustrate thefinal selector and its control circuit embodying the present invention.

l in theleVel marked Fig; 1 shows a connection including a primary finder UP, a secondary finder CS, a register E linked to the connection by means of a finder CE,

a primary selector SP, controlled by a group or relays in the register, a group. selector SG con-' trolled by a group with the group selector over findertCG,.and a final selector SF controlled by a final control circuit-F connected .with the final selector by means i offinderCR:

. Fig. =3 shows the circuit of the group selector SG and Figs. 3a and 3b the controlcircuit'there f I control circuit isarranged, as best shown i'nFig. 30, to stop the group selector by testing the 0 wires by the selection." ,The operas tionof the circuits of Figs. 3-30 is as follows:

Apreceding selectorin the chain tests aniidle group 'selector oyerj make-busy jack JO, a back contact of relay T and a resistance. A potential When thecircuit of the selector in use ,issfoun'd ground, front A8,: jack P, winding of Gt, brush pair of counting relays is 'i'ea'ched control circuit G connected 9 of a finder CG, the relayGt operates g and the battery connected to the back contact of CO.

Relay To and OC operate in parallel to ground at front Sh, the leads from the control circuit to the group selector are closed, and sequence switch It leaves position Z, its circuit being closed over cam B and front 06. The relay OC remains locked-up over back Lm, and cam D to ground which is connected also over a resistance, cam E, front Tel and brush 7' for operating relay C of the selector.

Relay Se is bridged across brushes a and b. On account of the low resistance of S2 the register E is started which in Fig. 2 is indicated by showing the impulse sender I connected to wire b and the starting relay D1 of the sender connected to wire a.

The relay Se operates, energizes Lb and receives the selective impulses. The relay Lb remains actuated during the receipt of the impulses, and relay OC becomes de-energized. At the end of the series of impulses, one or two pairs of counting relays (EC, F0) are locked-up depending whether the digit received was lower or higher than 6. When the slow relay Lb releases at the end of the series of impulses, R moves out of position .4, and a high resistance relay Hr is connected in series with the impulse relay Se in order to stop the register. From positions 1-4, Hr is short-circuited over cam S.

Between sequence switch position 4 in which the impulses are received and position '7 in which the selector is set, the diget received is transferred to the marker relays M1, M2, M4 or Me. For example, M2 is operated when sequence switch R moves from position 5 to 6 over cam H, front FC-Z, cams F and D to ground. When the switch leaves position 6, the locking circuit of relays EC and PC is opened and then closed again over cam.

F. in position 7, Whereas the relays E01 and F01 are locally fed over cam M in order to permit that the balance of the group of counting relays insure continuous hunting by the selector.

In position '7 the following circuits are closed: (1) relay S, cam R, brush e of selector SG to ground; (2) magnet of SG, brush p of finder CG, front To, back contact of test relay He, cams E andT'D to ground.

The operating circuit of thecounting relays is. closed from position 6, ground, cam'D, back S, armature FCG. Since F01 is operated, then EC2 becomes energized. In position 7 relay S is operated and EC2 and F02 are locked-up in series over back FCs, cams F and D to ground.

Assuming that the signal consists of two impulses,,relay M2 will be locked-up and the selector will hunt for an idle trunk in the second level. When the. selector SG leaves its home position the relay S releases the relay ECs operates. When the brush e of the selector contacts with the last terminal of the first level, the relay S is again operated and the relays EC3 and F03 are locked-up in series, the relays E02 and F02 become de-energized. The relays J2 and Jb are now energized by a, circuit over a back contact of J2, front S, cam G, front ECs, cam M, back Pol, front M2, back Ms, back M1, and earns Fand D to ground. J a places ground on He but even if the latter responds to the potential on the terminals of the last trunkin the first level the selector cannot stop because its circuit is closed over the back contact of J2, the front contact of S.

When the selector leaves the first level, S releases and He may then respondto the potential of 'a free trunk (ground at front contact of Jet,

winding of He, front Te brush t of CG, front Co, and brush d of selector SG). The relay Se is operated when He becomes energized and connects over its front contact a direct ground to the brush 7' of the finder CG. The relay T of the selector is actuated and locks up to the wire 0 of the preceding selector and by opening the a and 1) wires leading to the control circuit causes the de-energization of relays S2 and Hr. The relays Lb and Tc become tie-energized whereupon the sequence switch R is moved out of position '7 by a circuit closed over the back contact of Lb and cam B. The control circuit is now ready to receive a new call.

If the only free trunk in the selected level is the last one of the group, then the operation is somewhat different. When the selector leaves the last terminal of the first level the relay S releases and J2 is locked-up in series with Je and Jb. The relay E04 is operated over a circuit including the front contact of FC3, the back contacts of F04, 5 and e, the back contact of S and cam O to the ground. When brush e of the selector reaches the last terminal in the second level the relay S becomes energized and the relays Jo. and Jb become deenergized. However, J2 remains locked-up over a circuit including its right-had winding, front contact of S and front contact of J2 to ground. If this last trunk is free them the relay He operates and the control circuit is released as above described. On the other hand, if this last trunk is busy then the selector continues its rotation, S releases whereupon J2 releases. After each level is traversed one pair of counting relays is'energized which through the agency of relays P01 and, Pe2 insures that the hunt continue. At the beginning of the rotation, the

levels

1, 2, 3, 4 and 5 are marked over the back contacts of relays Pol. selector reaches the last terminals of the fourth level, the relay F05 locks up in series with the relay E05 and the relay Pcl operates and prepares a marking of the 6th, 7th and 8th levels.

The relay Pe2 is operated when the selector reaches the 8th level, the circuit extending over the winding Pe2, front Pol, cam J, front FC3. This relay prepares the marking of the levels 9 and 0. When the 9th level is reached the relay Pei is released and the relay Pez releases when the selector again returns to the first level.

Fig, 3c shows a modification of Fig. 3d. By means of this modified arrangement a trunk is engaged after the potential on the 0 wire and the presence of a ground on the a wire of the selector have been verified. In this'case the operation of relay Ho causes the operation of an additional relay AX which connects the a wire of the selector to a point connected over a high resistance to battery and also over the winding of an additional relay Ta having the same high resistance to ground. If ground is present on the a wire of the trunk then the relay Ta does not operate but a slow relay Se becomes energized and connects direct ground over its front contact to the relay T of the selector which as pre- 'viously described extends the chain towards the final selector and causes the release of the control circuit. If the trunk is busy then the relay Ta operates and disconnects relay He which by releasing restarts the rotation of selector SG.

Figs. 4, 4a and 4b illustrate the final selector and its control c rcuit. For the sake of simplicity the group counting relays in the control circuit never receives more than five impulses from the final selector under control during the the circuit extending from battery to the c wiper of the final selector winding of Ct, front B, brush t of CF, front Tc, front Ta to ground. The relay Ta was energized by a circuit including cam I and the front contact S in position 9 of the sequence switch.

If the called line is busy then the relay Ct does not become energized and the slow acting relay L (Fig. 4a) energized by a ground applied-thereto over the right-hand armature of Ta closes over its front contact and the cam N a circuit for moving the sequence switch out of position 9 whereupon the control circuit is released.

If the units impulses corresponds to the number of the first line of a P. B. X group then a relay T (Fig. 4a) is energized in series with the relay Ct of the final selector. If the line is free then the relay T operates and locks up over its second winding and short-circuits its first winding. When this happens the relay Ct of the final selector becomes energized. If, on the other hand, the line is busy then the relay T does not become energized and when relay L energizes the hunting for a P. B. X line is started.

In this case the relay Pb is actuated over a back contact of '1, front T01, brush 1' of CF and brush R of SF. If the units digit is even then the relay M1 which was de-energized will now be energized over the front contact of L, front Pb and back Ma. The relay M operates and reverses the connection of the relay S whereupon the latter becomes de-energized and causes the de-energization of Ta and thus of L. The power magnet of SF is again energized and the hunt continues. When the next terminals are engaged the relay 3' is energized by battery connected to the are d. The relay Ta is again operated and if the line is busy the relay L operates. Over its front contact it maintains energized relay Ma which was locked-up in series with M1 when relay L released. By opening its back contact the relay L causes the deenergization of relay M1. Relay S is now again connected to battery. Ta and L release and the final selector SF takes another step. If all the P. B. X lines are busy then the relay Pb releases as the wipers leave the next to the last terminal of the P. B. X group and the control circuit is released when relay R closes its front contact.

It will be noted that in Figs. 4a and 4b I have indicated in dotted lines those parts of the invention which have to do with the P. B. X hunting feature, the inclusion of which in the system is, of course, optional. Obviously, many other modifications will suggest themselves to those skilled in the art.

What is claimed is:

1. In an automatic telephone system, a plurality of numerically designated lines, means including a selector switch for connecting a calling line with a called line, said selector having sets of terminals arranged in numerical groups and a set of brushes cooperating with said terminals, a magnet for moving said brushes over said terminals, means for rendering busy said terminals, a control circuit, a control switch associated with said circuit, meansfor variably operating said control switch in accordance with various digits of the number of the called line, means for temporarily connecting said circuit with said selector, means for sending an impulse to said control switch from the selector for the engagement of each group of terminals by the brushes, means for operating said control switch by. the last-mentioned impulses, and test means in the control circuit responsive to the busy coridition of said terminals for controlling the circuit of said magnet.

2. An automatic telephone system according to claim 1 and in which said control switch comprises a set of counting relays, an operating circuit for said relays, and two relays controlling said operating circuit, one responsive to impulses representing the called number and the other to impulses sent from the selector.

3. In an automatic telephone system, a plurality of numerically designated lines, means including two groups of selector switches for connecting a calling line with a called line, each selector having sets of terminals arranged in numerical groups, a set of brushes cooperating with said terminals and a magnet for moving said brushes over said terminals, a control circuit for each group of selectors, a control switch associated with each circuit, means for operating one control switch in accordance with one digit and the other control switch in accordance with another digit of the number of the called line, means for temporarily connecting one of said circuits with a selector of the first group taken into use, means for connecting the other of said circuits with a selector of the second group taken into use, means in each selector for sending an impulse to the associated control switch for the engagement of each group of terminals, circuits for the selector magnets controlled by means in the associated control circuit, and means for releasing a control circuit upon the completion of the operation of the associated selector.

4. The telephone system in accordance with claim 3, and in which each control switch comprises a set of counting relays responsive to the impulses representing the called line and to the impulses sent from the associated selector.

5. The telephone system according to claim 3, and in which the other control switch is operated in accordance with two digits of the called number and means for operating said other control switch in accordance with an impulse sent from the associated selector for each terminal engaged in a selected group. n

6. In an automatic telephone system, a plurality of numerically designated lines, means including two groups of selector switches for. connecting a calling line with a called line, each selector having sets of terminals arranged in numerical groups, means for rendering busy said terminals, a set of brushes cooperating with said terminals and a magnet for moving said brushes over said terminals, a control circuit for each group of selectors, a control switch associated with each circuit, means for operating one control switch in accordance with one and the other in accordance with two digits of the number of the called line, means for temporarily connecting said one circuit with a selector of one group taken into use, means for connecting the other circuit with a selector of the other group taken into use, means in the selectors of said one group for sending animpulse to the-associated control switch for the engagement of each group of terminals, means in the selectors of the second group for sending first an impulse to the associated control switch for the engagement of each group of terminals and then an impulse for the engagement of each set of terminals in a selected group, circuits for the selector magnets controlled by means inthe associated control circuit, test means in each control circuit responsive to the busy condition of the terminals in the associated selector selection of the tens as well as during the selection of the units. The relay S is bridged across the e and d brushes of the selector. This relay operates every time the brush (1 engages a terminal connected to the positive pole of the battery if the tens digit is even or to the negative pole of the battery if the tens digit is odd.

Only the brush 6 is used for selecting the units. The relay S is then connected to ground if the units digit is odd and to the positive battery if the units digit is even. The hunting for an idle PBX line is controlled by a current reversing relay. A preceding group selector stops at the terminals of a free final selector which applies a potential over the make-busy jack OJ and the back contact of relay C0. Then, as in the case of a group selector, a potential is placed on the b wire by the register circuit. The relay St (Fig. 4a) becomes energized and causes, in turn, the energization of relays B and Cs (Fig. 4a)

The finders CF of all the idle control circuits will start hunting for the final selector taken into use, the circuit extending from battery, winding of magnet CF, back To, front C's, jack OJ, cam C and back Gt to ground. When the selector is found the relays Gt and Sn become energized. Then the relays To and Tel become energized in parallel, ground being applied at the front contact Sh. These relays connect through the conductors of the control circuit.

The relays R and B of the final selector are operated in parallel, ground being applied over brush 7' of CF, front To and cams K and J to ground. The sequence switch R is moved out of position 1 into position 4 by a circuit extending over cam B and front T01 to ground.

The relay Sa is bridged across the wires a and 12, starts the register and receives the numerical impulses therefrom. In response to the first impulse it causes energization of relay Lm over cam E which remains actuated during the sending of the impulses. Relay which was energized over cam C when the sequence switch passed through position 2 becomes de-energized upon the energization of Lm and prepares the circuit for moving the sequence switch out of position 4. At the end of the tens series of impulses a pair of counting relays I0 and Is is locked-up if the digit is lower than six and two pairs are locked-up if the digit is higher than six.

When at the end of the series of impulses the relay Lm releases, the sequence switch R leaves its position 4, ground being applied thereto over cam J. From position 4 to position 5 the marking relays M1, M2, M4 and M6 are supplied with current and locked-up in accordance with the following table:

Relay Digit Received t t d Beginning with position 4 the locking cir-' cuit of the relays Ic and Id is opened and then reclosed in position 5 by cam J. The units are then received on thecounting relays in the same manner as the tens. In position 5 the circuit of the final selector magnet SF is closedover brush p of CF, front T01, back L, cam G, back Eco, cam N to ground. The relay S is actuated every time the brush d engages a terminal connected to the negative battery if the digit is even (relay M1 de-energized), or to the positive battery if the digit received is odd (relay M1 energized). If, for instance, the digit 4 was registered by the marking relay, then the relay N4 is locked-up and the relay E04 is operated over the following circuit: Battery, winding of Em, back Fdi, front M4, back Ms, cam I, back S to ground.

When the brush d of the final selector engages a terminal connected to the negative pole of the battery, the relay S is actuated and the pair of counting relays E02 and Fd2 is locked-up. When the wiper of the selector engages the next terminals which are connected to the negative pole of the battery, the relay S is again actuated and then falls off and the relays Em and FdO are locked-up. At this moment the driving circuit of selector SF is transferred to the ground at the back contact of S over the left-hand contact of Eco. When the brush (2' of the selector contacts With the next terminal (the 4th terminal connected to the negative pole of the battery) the relay S becomes energized and stops the selector SF, the wipers of which engage the terminals corresponding to the digit 4,

The units impulses are received-on the relays I0 and Id. In response to the first impulse the relay Inn becomes energized and remains lockedup during the sending of the impulses. Upon the termination of the units impulse the relay Lm falls off and the sequence switch R moves out of position 5 The high resistance relay H is then energized in series with relay Sa over the a and 12 wires in order to maintain the control circuit and to prevent the energization of the supervisory relay of the connection circuit.

When the brush of the selector reaches the terminals designated by the impulses the relays E00 and Fdo are locked-up and the sequence switch is moved out of position 6 by a circuit including its cam B, front Fdo, front S to ground. The relays E0 and Fa are released because their locking circuit is opened in cam N.

When the sequence switch R reaches position 8 it will cause the setting of the selector SF in accordance with the units impulses. The circuit of the driving magnet is the same as during the tenths selector but the marking relays, after position 6 (in which they were locked-up over cams L and M) are again fed over cams O, P, Q and R depending on the units digit received. If the unit digit is 1 the relay M1 is energized and connects relay S to ground. When the brush e of the final selector contacts with a terminal connected to battery, the relay S will become energized and stops the final selector because the pair of counting relays E00 and Fan are locked-up.

Beginning in position 7%, the ground at the back contact of relay S is connected over cam I towards the group of relay EcFd, the circuit in the present case extending over back Ms, back M4, back M2, front M1, back F40, winding E00 to battery.

When the final selector contacts with the terminals represented by the units digit, the sequence switch R is moved out of position 8 by a circuit over cam B, front PM to ground at the front contact of S.

If the selected line is free then relay Ct of the final selector becomes energized and locked-up,

also controlling the associated magnet circuit, means for releasing said one control circuit upon the engagement by the associated selector of a set of idle terminals in the desired group, and means for releasing the other control circuit upon the engagement of the desired set of terminals in the desired group.

Y '7. The telephone system according to claim 6, and in which means are provided in the second group of selectors for hunting for an idle set of terminals in a selected group, and means in the associated control circuit responsive to the busy condition of terminalsfor controlling the lastmentioned means 8. The telephone system according to claim 6, and in which the one control switch comprises one set of counting relays and the other two sets of counting relays.

9. A telephone system according to claim 1, and inwhich said control switch comprises a plurality of pairs of counting relays forming a chain, circuits for energizing andlocking up one pair of said relays if a digit of the called number has less than a given valueand two sets if it has a given value or higher, a marking relay for each pair of counting relays and operated'in response to the operation thereof, a circuit for operating a set of pounting relaysupon theengagement of each group of terminalsbythe selector brushes, means controlled by said marking relays to close the magnet circuit for operating said selector to hunt for a set of idle terminals in the selected group, two relays also controlling saidmagnet circuit to operate the selector to continue hunting for an idle setof terminals if all the terminals in the selected group are busy, an "energizing circuit for one of said two relays closed upon the energization of the last pair the counting relay chain, and an energizing circuit for the other of said two relays jointly controlled by theiirst one of the two and. an intermediate pair of counting relays." I y ,7

10. A telephone system according to claim 1, and inwhich said control switch comprises two sets of counting relays, a first, impulse relay in said control circuit responsive .to impulses representing two digits of .thenumerical designation of the called line, a circuit for operating the first set of countingrelays controlled by saidimpulse relay in response to the firstdigit, mean for releasing the counting relays of, the .firstset and.

operating them. under the, control of the impulse relay .in .accordancewith the, second digit, a cir-.

cuitlfor the selectormagnet closed under the control of said counting relays, revertive impulses sent by the selector to said control circuit depending on the extent of movement or its brushes during the-movement of the brushes irom one group of terminals toanotheriand also during the movement from oneset of terminals .to another in a selected group, a second impulserelay in the control circuit responsive to said Irevertive 'impulses, -a circuit for operating the second set of counting-relays controlled by the second impulse relay, in accordance withfthe revertive impulses representing both operations of the selector, and means under ,the control of the second set of counting relaysioropening the circuit of the selectorvmagnett, I v I 11. A telephone .system according to claim,, 1, and in whichsaid control switch comprises two sets ,ofcountinghrelays afirst impulse relay in saidcontrol circuitresponsive to impulses representing two digits ,or the numericaldesignation of the called line, a circuit for operating the first relay'in accordance with the second digit, a pluralityof'marking relays, circuits for operating one of'said marking relays depending on the op-' erations of said'first set of counting relays, a'circult for the selector-magnet closed bysaid marking relays, revertive impulses sent by theselectoi" to said control circuit depending on the extent of movement of its brushes duringthe movement of thebrus'hes from one group of terminals to another and also during'the movement from one set' of terminals to the other in the selected group, a second impulse relay in the control circuit'responsive to said'revertive impulses, a circuit for operating the second set of counting relays controlledzby the second impulse relay in accordance with the revertive impulses representing both operations of said selector, and means under the joint control of said marking relays and the sec'-' ond set of countingrelays for opening the circuit of the selector magnet. 12. In an automatic telephone system-,a' plurality of numerically designated lines, means in cluding a group of selector switches for estab-' lishing a conversation circuit between a calling and a called'line, each selector having a plurality of sets of terminals arranged in groups, each' set of terminals comprising two' in the conversation circuit and a test terminaL'said selector having three brushes cooperating'with s'aid terminals, a magnet in each selector for movingsaid brushes over said 'terminals,"a'control circuit, a'control switch associated with said circuit, means for temporarily connecting said circuit witha sele'c tor taken into use, means for operating-said con-" trol 'switch'in accordance with the number 'ofthe called line,means in each selector for sending an impulse to said control switch for the engage merit of each group of terminals, a'first relay in said control circuit having a winding connected withthe brush of the selector cooperating with the test terminal, means for applying a distinctive potential to the test terminal and to one of the terminals in the conversation circuitga second relay in'the controlcircuit operated upon the energization of the firstrelay, a third relayin the control circuit operative thereupon and responsive to the distinctive potential 'on the con versation terminal engaged by the "selector brushes,'said third relay having a contact in the circuit oithe first re1ay,'and means for releasing the control circuit and-'seizingaset of terminals alsocontrolled'by the third relay.

13. In an automatic'telephone system, a p'lurality'of numericallyfdesignated lines,'means including a group of selector switches for es'talo-' lishing a conversationcircuit between 'a calling and a called line, each selector having a'plurality of sets o r terminals arranged in groups each set of terminals comprising two" in the conversation" circuit and two other terminals, said selector having four brushes coo-peratirig with said terrni nals,'a magnet in each selector for moving said brushes over said terminals, a control circuit,'a control switch associated with said circuit, means for operating said control switch in accordance with the number of the called line, means for temporarily connecting said circuit wthjag selector takeninto use, means including brushcooperatingwith one of two other terminals for sending an impulse to said control switch for, tl eengagementof each group of terminals, afirst relay in said control circuit having a winding connected withthe brush of the selector cooperating with the second of the two other terminals, means for applying a distinctive potential to the last-mentioned terminal and to one of the terminals in theconversation circuit, a second relay'in' the control circuit operated upon the energization of the first relay, a third relay in the control circuit operativ thereupon and responsive to the distinctive potential on the conversation terminal engaged by the selector brushes, said third relay having a contact in the circuit of the first relay. andmeans for releasing the control circuit and seizing a set' of terminals also controlled by the third relay,

14.In an automatic telephone system a plurality'of numerically designated lines, means including one of a group of selector switches for establishing a conversation circuit between a calling and a called line, each selector having sets of terminals, each set comprising two terminals in the conversationcircuit and three other terminals, a set of five brushes for each selector cooperating with said terminals. a magnet in each selector for operating the brushes successively to engage said sets of terminals, a control circuit, means for associating the control circuit with a selector taken lnto'use. a first set of countin relays in said circuit, a first impulserelay for Controlling the operation of said counting relays, a circuit for said impulse relay including two brushes of said selector cooperating with two of the three other terminals, distinctive potentials applied to alternate terminals with which one of said two brushes cooperates, distinctive potentials applied to alternate terminals with which the other of Said two brushes'cooperates, test potentials applied to the third of said other terminals, a test relay in said control circuit responsive to the test potentials, a second impulse relay for controlling said set of counting relays, means for operating said second impulse relay in accordance with the numerical designation of the called line, a second set of counting relays controlled by the first .impulse relay, and a circuit for the selector magnet controlled by said test relay.

'15. "In'an automatic telephone system, a plurality of numerically designated lines, means including one of a group of selector switches for establishing aconversation circuit between a calling andacalled line, each selector having sets of terminals, each set comprisin two terminals in the conversation circuit and four other terminals, a set'of six brushes for each selector cooperating with said terminals; a magnet in each selector for operating the brushes successively to engage said sets of terminals, 2. control'circuit, means for associating the control circuit with a selector taken into use, a first set of counting relays in said circuit, a first impulse relay for controlling the operation of said counting relays, a circuit for said impulse relay including a rectifier and two brushes of-said selector cooperating with two of the four other terminals, ground potential applied to alternate terminals and negative potential applied to-the other terminals with which one of said two brushes cooperates, negative potential applied to alternate terminals and positive potential to the otherterminals with which the other of said two brushes cooperates, test potentials applied to the third, of; said four other terminals, a first test relay in said control circuits responsive to said test potential and controlling the direction in which thecurrent flows through the impulse relay, test potentials applied to the fourth of said four other terminals, a second test relay in said control circuit responsive to the last-mentioned test potential, a second impulse relay for controllin said set of counting relays, means for operating said second impulse relay in accordance with the numerical designation of the called line, a second set of counting relays controlled by the first impulse relay, and a circuit for the selector magnet controlled by said test relays and two sets of counting relays.

16. An automatic telephone system according to claim 14, and in which the second impulse relay is responsive to impulses representing two digits of the numerical designation of the called line, a circuit for operating the first set of countin relays controlled by said second impulse relay in response to the first digit, means for releasing the counting relays of the first set and operating them under the control of the second impulse relay in accordance with the second digit, a plurality of marking relays, circuits for operating one of said marking relays depending on the operations of said first set of counting relays, the circuit of the selector magnet being under the joint control of said marking relays and the second set of counting relays. 1

1'7. An automatic telephone system according to claim 1, and in which said test means comprises a'normally inoperative relay, and means for rendering said relay operative only When there is agreement between the operation of the control switch in accordance with the called number and the functioning of the selector.

18. In an automatictelephone system, a plurality of numerically designated lines, means including a group of selector switches for establish ing a connection between a calling and a called line, each selector having a pluralit of sets of terminals arranged in groups'and a set of brushes cooperating with said terminals, a magnet in each selector for moving said brushes over said terminals, a control circuit, a control switch associated with said circuit,.means ,for temporarily connecting said circuit with a selector taken into use, means for operating said control switch in accordance with the number of the called line, a circuit for the selector magnet closed upon the operation of the control switch, means in each selector for sending an impulse to said control switch for the engagement of each group of terminals by the selector brushes, means for applying a distinctive potential to one of the terminals of each set to indicate its busy condition, a. relay in the control circuit responsive to the distinctive potential on the terminals closing thecircuitv of the selector magnet while the selector brushes enage busy terminals in the selected group, and means for operating the control switch in accordance with the impulses sent by the selector after engaging all the terminals in a group and finding them busy.

19. In an automatic telephone exchange system, a plurality of numerically designated lines, means including a group of selector switches for connecting a calling line with a called line, each selector having sets of terminals arranged in groups and a set of brushes cooperating with said terminals, a magnet in each selector for moving said brushes over said terminals, a control circuit, a control switch associated with said circuit, means for temporarily connecting said circuit with a selector taken into use, means for operating said control switch in accordance with the number of thecalled line, a set of counting relays in said control circuit, a circuit for marking a counting relay in accordance with said operation of the control switch, means in each selector for sending an impulse to said counting relays for the engagement of each group of terminals, and. a circuit for the selector magnet jointly controlled by said control switch and. the fnarked counting relay.

JEAN R. A. ESCANDE.

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

UNITED STATES PATENTS Number Name Date 1,762,763 Collis June 10, 1930 1,291,894 I-Iovland Jan. 21, 1919