US1051894A - Special-call telephone system. - Google Patents

Description

A. E. KEITH. SPECIAL CALL TELEPHONE SYSTEM.

Patented Feb. 4, 1913.

' APPLICATION FILED MAY 2, 1911. 1,051,894.

3 EHEETS-SHEET 1.

42mm 8. M

a, 66 Ma MTYVESSES A. B. KEITH.

SPECIAL CALL TELEPHONE SYSTEM;

APPLICATION FILED MAY 2,1911.

1,051,894, Patented Feb. 4, 1913.

3 SHEETS-EHEBT 2.

N g llllllllllllHl W/TA Zlfi'SES F f/VKENTOK:

A. E. KEITH SPECIAL CALL TELEIHfiNE SYSTEM.

APPLICATION FILED M A w I UNITED STATES PATENT OFFICE.

ALEXANDER E. KEITH, OF HINSDALE, ILLINOIS, ASSIGNOR TO AUTOMATIC ELECTRIC COMPANY; OIICHIOAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

SPEOIALCALL TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Feb. 4, 1913.

Application tile d May 2, 1911. Serial No. 624.558.

To all whom. it may concern:

Be itknown'that I, ALEXANDER E. KEITH,

. systems in which either all or adpart of t ie callin connection .is establishe by means contro led by the calling subscriber, and more es ecially to a system of this kind in .which t e automatic switches are controlled by rotary or other similar calling devices atthe substations. In such a system it is necessary, of course, in order to extcndthe-call from any calling line, for the calling subscriber t0 first take down the receiver, and to then operate the rotary or other suitable calling device, whereby either all or a part of the calling connection is then extended from the calling line. Ordinarily, in a s stem of this character, a calling subscri er cannot obtain connection with the substation of any other subscriber, or even with the telephone of an exchange 0 erator,'e'xeept by first operatin the 'sai rotary 'or ot ier calling-device at e callin substation. In some cases this is extremely o jectionable, as itoften occurs that-a callingisubscriber should have a res case as quic ly aspo sible, and without. eing under the neoessi y of first operating the rotary callin device.

The ob ect of my invention is, t erefore, to provide a system of this dgeneral character in, which, revision is ma for'en'abling a calling a scriber. to converse-with an oporator without the necessity of -first operatin the rotary calling device at the calling su station. n..this way, for example, an alarm of tire can be turned in very quickly and sim ly' byfthe removal of the receiver at the ca ling substatiom Also, .this expedispecie cat can be employed. .for enabling an call .E

ing subscriberto converse with a ou le op-' erator ,or withpan-operatorIforfsome other l purpose, by simply. takingdownthe receiver at the calling substation, and without the necessity of first operating thelrotary calling device. Regular calls can be made in t li'e, usua l.way v "W c J in the well-known manner.-

each callin meets and t isconnects, through the medium In Fig. 1't

operating the rotary But calls for certain special purposes, such as those indicated, or of any .other desired character, can lie-made by simply removing the receiverat the calling substation.

To these and other useful ends m tion contemplates a telephone wit invenwhich subscriber automatically conof switching mechanism controlled from the calling substation, before the call reaches the called line.

It further contemplatesa telephone which is common to a plurality of first selectors, being connected therewith, and which is automatically disconnected from the calling line by the initial operation of any first selector, whereby the said tele hone is connected with each and every cal ing line, and then automatically disconnected therefrom by the initial operation of the selector before the call reaches the called line.

It further contemplates a system in which means are provided for enabling an operator to listen in on every calling line as soon as the receiver is removed at the Calling substation, and in. which means are provided for preventinf: the operator from listening in on any cal in lines overwhich the calls have pro esse' to the point where the rotary ca ing device has been operated to control the automatic switches.

In the accompanying drawings, Figures 1 and 2 taken together show a complete connection between a-calling substation A and a called substation A in a systemin con- .neotionwith which I have chosen to illus- 'trate my invention.

Fig. 3 is a diagrammatic representation of a portion of the central otfice ap aratus.

lie lines of the substation A terminute at the central oflice in an individual or line switch 0. The line switch 0, together with a number of similar switches, is controlled by-a socalled master switch D and has common access to a plurality of trunk lines leading to first selector switches A group of-firstselectors E has common access to, anumber' of second selectors F, which in-turn have'access to connector switches L. The'connectors have direct access'to the subscribers lines. The connector- L is represented as having been brought into connection with the e of substat1on-A'.-to which there is allotted at the central otll'oe thezline switch C'.,

5 prises-theusual receiver 2, switch hook 3 .At -:(Fig. 1);:there. is represented an ope'rators-talking set a I jThe' automaticsubstation with which I have chosen to'illustrate my invention comtransmitter; 4,;iringer, 5' and condenser. 6. Since it ,is 'an-autom'atic substation, -.itis provided with a'pair ofimpulse springs 7 and 8 and an impulse wheel 9. The impulse wheel9jcarries on'its periphery a number of impulse teeth 10 'and is secured to a shaft 11, towhich there is also secured a dial; (not shown) rovided with. fin er holes.. By m'ea'ns'o the dial the impi se whcclmay be rotated forward, after which it may be returned to normal ppsition by a spring (not shown). During t s backward movement of theimpulse wheel, each of the teeth 10 which passes the end of the spring 8 momentarilyseparates said spring from the a ring 7. The number of teeth which are t as carried net the end of the spring 8 depends upon't e digit called.

The line switch C, which is individual to the line of the substation A, and the master switch.D are of the general type disclosed in British Patent No. 26,801 0 1906, and in the. American Telephone Journal of New York, N. Y., of J une 6, 1908, buthaving a somewhat modified construction. As illustrated herein, the line switch C comprises the usual plun er 12 (Fig. 3) attached to the end of the 'p unger arm 18, which is controlled by the magnet 14. Besides the lunger arm 13, the magnet 14 also contro s the relay armatures 15 and 16, and comprises four windings, namely, a pull-in winding 20, a holding and cut-off winding 17, a line winding 18 and an auxiliary winding 19. The core of the magnet 14 is provided with a lateral projection 21 near the center of its length, by means of which the ma et is attached to the bracket 22 upon which the armatures 15, 16 and 18 are mounted. With this arrangement the magnetic circuitpf the windings 17 and is madesepara'tefrom that of the windings 18 fore the armatures on one end of the magnet are not affected by the windings upon the other end. .Of the, two windings u on the upper: end of the ma et, the --winding 20 is the stronger and, w en energized,-opcrates both the'pl ture -15. qThe' w nding 17 is strong enou h to" perate only, the armature 15qand 'ho d the-plunger'arm 18 in operated 'tion. It'cannotattract the plunger arm in its normal is attracted, the plunger on the 'end'thereof is forced into'a grou "of rings, forcing the springsm}, 25, .2 and 9-into ment withthesalringfi 24, 26, 28 and 8, llpectivelyr Al oug only one 'grou of (ea-soil. shown, each. switc C es'g iiied wi number of suchgrqnns and 19, and there-,

unger arm 18 and arms positiom When the plunger arm 18 of s rin each group forming the terminal f a t runk line leading to a selector E. Each of these trunk lines is common to a number of line switches C. The plungers of idle line switches normall engage a socalled plunger shaft 31 ig. 3), through the 'medium of which they are held oposite idle trunk lines by the master switch which is common to a grou of line switches. As herein represented t e master switch D com rises, among ot er details, a ratchet wheeP32, motor magnet 33, relays 34 and 35 and a bank of contacts comprising a common segment 36 and an indivi ual segment a for each of the trunk 30 lines to which the switch C has access. The ratchet wheel 32 is connected with the plunger shaft 81 (Fig. 3) by the link 87 and shaft 88 in such a 'manncr that the rotary motion of said wheel imparts td the plunger-shaft 81 an oscillator motion about-the shaft 38, to move the idle plungers back and forth in front of the trunk terminals. Attached to the shaft 38 there is a locking plate 39, provided near its outer no edge with a number of o enings 40 which are adapted to be engaged by a pin 41 on the end of the armature 42 of relay 35. The openings 40 are so spaced that the pin 41 can engage one, of them only when the plunger-s which are in engagement with the pin er shaft are directly opposite the-termin fis of a trunk line. Attached to the shaft 38 there is a wiper 43 which always keeps the common se connection with the individual segment a which corresponds to the trunk line in front of which the idle lungers are being held by the lunger shait 31.

The rst selector E is of the disclosed in United States Letters'Patent 815,321, granted March 13,1906, to Keith, rickso'n. and Erickson, being somewhat modified, however, in' order system in which the central is controlled from'the calling substation over the two .sides' of the line in series. This selector comprises the usual wipers 44, 45 and 46, carried upon a shaft (not shown) to operate in a 'thevertical ma et 47 and a rotary motion controlled by t e rotary magnet 4.8. The usual side. switch, comprising the wipers 51 and 52, is controlled by the private magnet 53 in a' well-known manner. leasing the switch are provided in'the usualrelease magnet 56; 'T e springs 57 and 58 which'are included in the circuit of the release magnet are separated by the arm 59,

as said shaft is in its lowest position. The s rings 187 and 188 are held in contact by t 0 arm 59 as long as the switch shaft is in its lowest position, but become separated as tsoon as the shaft is raised one or more steps.

ment 36 in electrical general type office apparatus 11L which .has a vertical motion controlled by Means for rewhich is attached to the switch shaft, as long The inechanisinof the selector E is released immediately upon" the energization of the release magnet', fra ther than b its deenergization'as shown in the said se ector patent. The armature 60 of the rotary magnet 48 has no finger for pressing down the armature of theprivate magnet 53, as shown in the selector patent, but controls the said private magnet electrically through-the medium of the springs .49 and 50. The. calling subscriber controls the operations of the switch through the medium of the double wound line relay 62. The relays- 63' and-64 are relays that de'cnergize slowly after their energizing circuits have been broken. This slow action is usuallyobtained by securing a heavycopper rip around one end of the core of themugn'et. he wipers of the selector E are adapted to en age a bank of contacts forming the termina s of trunk lines leading to selectors F. Each trunk line is commonto a number of selectors E. v

' The selector F is like the selector E, with the omission of the ofi normal springs 137 and 138.

,The operators' talking set 0 (Fig. v1) comprises a receivcp 139. transmitter 140 and induction coil 129.' Thisoperators set is common to a number of first selectors E. Allotted-to eachselector there is a relay 136 for establishing a talking connection between the operators set and the selector.- The connection between the operators set and the selector is also controlled by the springs 1-87 and 138 which are controlled.

t. ie arm 59 in the manner already ex laine The connector- L"(Fi v3)' is of.t e general type disclosed in U iited States-Letters Patent :815,1'2' 6, granted March 18,1906,

to Keith,'Ericl-rson and Erickleon but; like-'- the selectors, is 'm'odifiedsome'whatto oper-- ate in a two-wire system. Likethe selectors, the 'connector comprisesjaset oi wipers 103,

104- and 105carried upon a shaft-'.(not' shown) which is control ed bythe vertical magnet 107 and ,rotary ma usual side switch is controlle bythe' rivate magnet 108 in the usual manner. he release,.magnet109"-is similar to-the release magnet 01 the, selector switch. The ringer,

relay =110is provided for the piurpose of connecting the ringer'generator withthe called line afterfconnection'haa beenicompleted therewith. The talking-batteryciir rent is fed to the calledrsubstationthrough the winding of'the'so callediback brid' re layj;111. Thetalking circuit throng the connector includesitwo condensers vi112. and

Having given a general description of the apparatus, I- will now describe its operations in detail. It will'.-first be explained how a cal ing subscriber A obtains connection with another subscriber A, after which itwill be described how's subscriber may communiet 106. The

cats with the operator at O; .In order to call' another subscriber the calling subscriber must first remove his receiver and then operate his calling dial'for, each of the digits of the number of the line desired. In-order to communicate with the operator, all that the-callingfsubscriber need do is s imply remove his'receiver from theswitch hook.

assumed that the number of the Substation A is 2220. When-the receiver is're noved from the switch hook preparatory to making a call, the said hook rises, permitting spring 211 to disengage spring 213 and en'- gagc spring 212, whereby the circuit of' the na bi'i ge consisting of the transmitter .4, teceiver 2 and' iinnilse springs 7 andtBis closed'across the ine conductors 66 and 67. This completes an ener izing circuit for the line winding 18 of' te line-switch C. This circuit Extends from through springs 68 and 69, line. 67, hook switch springs 211 and 212, impulsesprings 7 and 8, receiver, 2, transmitter 4,'line' 66, sprin s71 and and winding 18 to batt'ery end 74, thence through the battery 13 to ground G. The winding'1 8," upon enerizinig, attracts the armature 16, which orces'the spring 73 into engagement. with spring 68, thereby completing a circuit t '16 from breaking the circuit of the winding -following manner: The .forcin 23. and 25. into engagement with springs 24 and 26, respective ,'by the plungeroithe sw tch 0 extends t e line connection tb the selector E,'whe reby' the relay. 62 becomes energized over. a circuit extending from ground Gthrough the lower winding of said'rela springs 101 and 102, s'prings'26 and 25, t ence to and through-substation A and back over the other side of the line, through the line switch springs '23 and 24, springs 134 and 135, u per winding of relay 62. and lower wincing of relay 13 6 to In the following description it will be' r 5 and condenser (E is'bi'oken, an'd a/ ground G deenergize. slowly'to prevent thearmature 20 before-the circuit of the holding winding ;17 is closed. This circuit is closed-in the of springs the battery lead 74. The'relay 62, upon energizing, completes a circuitif rom ground use 'attractsita armature 42, withdrawing e the'plungerauntil the'ncx't opening in the said *circuit extending, from ;through sprin s-' 81' and 82,

'by'the switch 10 had been busy,

G 'through springs 78 and-79 and relay 63 to the battery lead"74. The relay 63, upon energizing,complctes the circuit of the holding winding '17 of the line switch C, ound G I I 8 and 27, andiwindin'g 1 to battery .lead 74. -The current in winding 17 serves to. hold the plunger'arm 'j13.and'.farmature. 15 in an operated 'osition'a'fter-the circuit of winding'20 is roken by the falling back of the armature 16.--The energization of the relay 63' at the selector E also extends a guarding ground over the conductor 83 to the private ank-contactsof' the calling line in the banks of all connector switches WhlCll have access to that line.

I The engagement of the line-switch bank springs 29 and 30 completes an energizin circuit for the relay 34 of the master switc D.. This circuit extends from ground G through springs 29 and 30, contact 84, wiper 43, segment36 and relay 34 to battery lead 74. The relay 34, upon energizing, operates to close the circuit of relay 35, which in tufln t e pin 41 from the plate 39 and comp ting the circuit of the motor ma et 33. This circuit extends from. groun G through magnet 33, .interruptersprings 85, contact point 80 and armature 42 to battery lead 74. As long as the armature 42 engages contact point 86, the magnet 33 operates in a manner similar to that of a buzzer, to rotate the ratchet wheel 32 to advance the plungers that are in lockin engagement with the plunger shaft. A ter the plungers have een advanced a short distance, the wi r 43 passesoff the contact 84, thus allowing the relays 34 and 35 to deenergize. The armature 42 does not fall back immediately upon the deenergization of relay 3:"), because the o ening in the. plate 39 which was engage by p in 41, has-passed out of register therewith; {After the relay 35 is deiin'ergized, the master switch still continues to advance late 80 paseesa nder the pin 41, whereupon, itthe corresponding'trunk, line isidle, the pin 41 drops into said opening, locking the plunger shaft against. further rotation and allowing" theiarmatur'e' 42 [to disengage contact oint 86'- to break the circuit of magnet 83, f the-next trunk after the one'eeized th w p 48 would have-foundthe corres ending con grounded,

energized while the next opening was pass in under the pin 41 thereby causing the id e 1plungers to be-advanced past the busy trun ,to, an -.idle one. .Duringthe time the masterfswi'tch D is operati the all-in win I 20o! all the line sw escon rolleda I master ,are

from the battery and connected to the busy signaling machine M. Thus any subscriber who attempts to make a call while the plunger of his line switch is being moved from one trunk to another will not be able to operate the line switch, but will receive a busy signal, due to the inductive relation of the line winding 18 to the winding 19, which is connected to the busy signaling machine.

The foregoing are the operations which take place immediately upon the removal of the receiver at the calling substation. The calling subscriber now operates his calling dial in the usual manner for the first digit 2 of the number desired. As the impulse wheel 10 returns to normal position after being rotated with the. dial for the digit 2, the impulse springs 7 and 8 are momentarily separated twice. The separation of the impulse sprin 7 and 8 breaks the energizing circuit of t is selectorJine relay 62, allowing it to be momentarily deinergized. Since the relay 63 is slow acting, it does not have time to denergize during the momentary interruption of its circuit by the dener m'zation of the relay 62. Consequently, the de energization of the line relay com letes an energizing circuit for the vertica magnet 47. This circuit extends from ground Gr through the springs 78 and 80, springs 87 and 89,- relay 64, vertical magnet 47 and side switch wiper 51 to the battery lead 74. Since the digit called is 2, the vertical magnet receives two impulses over this circuit, operating to raise the shaft and wipers two steps to a osition opposite the second row or level of bank contacts. The relay 64,

which is included in the energizi circuit of the vertical magnet, is energize by the first impulse through it, but, being a slow acting relay, its circuit is not opened long enough to permit it to deiinergize until after the last impulse forthe digit is transmitted. In its energized position therela 64 closes a circuit extendin from ound through the springs 90 an 91 an private magnet 53 to the battery lead 74. After the last impulse for the first digit is transmitted, the relay 64 deenergizes and opens, the circuit of the private magnet, which inturn deenergizes and permits the side switch to pass to seeond'pos1t1on.' In ssing from first to sec- 'end position the. side switch wiper 51 diaconnects the battery from the vertical magnet 47 and closesa circuit throughtherotary magnet 48. This circuit extends from' ground G through interrupters rings 50 and 92, rotary magnet 48 and side switch wiper 51 to battery lead 74. The magnet 48, upon energizing, attracts its armature 6,WhlCl1 rotates the switch shaft and wipers one opens the circuit of its own magnet at e interrupter springs 92, and closes the circu t of the I I I I rivate magnet 53 by forc ng spring 50 mto engagement with grivate magnet I 8 G from thepriva'te magnet. If .the first trunkupon the contacts otwhichthe selector wipers have just been rotated is idle, the

etinergizes when the ground is disconnected and allows the side switch to ass .to third. position. If, howover, the rst trunk is already inuse, the private wiper 46 finds the first contact which it engages grounded, and maintains the private magnete'nergized-over a. circuit extending from said grounded bank contact through .the wiper 52and magnet 53 to battery lead 74; The private magnet thus locks the side switch in second position, and the rotary magnet continues to'operate in a manner similar to that of a buzzer to advance the wi rs ate by step until the private wiper 4 engage a non-grounded con tact of an idle trunk, whereupon the private magnet deenergizes and permits the third position. At

side switch to pass t the instant the side s ptch asses to third position a guarding po entia is established at the selector private bank contacts'of the trunk seized by the selector E. This arding potential extends from groun G through the springs 81 and 82, side switch wiper 52 and private wiper .46 to the selector private bank contacts. The passage of the side switch; wiper to third position also completes an energizing circuit for the relay 98. This circuit extends from ground G" throu h the springs 81 and 82, relay.

98.-and si e switch wi er 51-to the battery lead '74. The rela 9 thereupon energizes and, by. shifting t e springs 102 and 134 out of en gement' with the s rings 101 and 135 and into, contact with t e springs 93 and 94, respectively, disconnects the line relay 62 from the line and extendsconnection throu h the shaft -wi era 44 and 45 to the secon selector F. T e rela 62 thereupon detinergizes and disconnects t e ground from the slow acting'relay 68, which dc'einergizes and disconnects the round Ci from the relay [98. Before thishappens however, a new holding circuit is provide for this relay by the selector F in the following'manner: As soon its connection is, extended to said selector, its line relay 95 becomes ener- I gized in the same manner-in which the relay 62 of the selector E-was ener zed when the connection was firstexten'de thereto. The relay 95, u'pon energizing, completes a circuit throu ith'e'slow, actmg relay 96, which corrcspon s totheffr'clay68 of selector E. The relay 96, uponenergizing com letes the circuit from ground G. throng] the springs 97 and 99, conductor 210, )rivate wi er 46, side sw1tchwiper-52,4rc ay 98 and side switch wiper 51 to the battery lead 74. The energization otthe relay 96 of the selector F also provides a holding circuit for the winding 17 of the line switch C after the relay 63 of the selector E' has deene'rgized. i

When the calling subscriber operates his calling device for the second digit 2, the

circuit of the line relay 950i the second selector F-is broken twice bythe substation impulse springs 7 and 8. The selector F operates in response toflthese impulses in exactly the same manner as explained for the" selector, E to raise its wipers two steps and then to automatically rotate them onto an idle trunk line 131-132 leading to a connector L.- The relay 114' of the selector F is then energized in the -same-manner as-explained for the relay 98 of the selector E and disconnects the line relay 95 from the line. The relays 95 and 96 thereupon deenergize, causing the ground Gf to be.dis-

connected from the trunk release conductor 210. Since the relay 96 is slow actin a new holding ground for the switches and C is provided b the connector L before the said relay 96. as time to deenergize. This holding ground is rovided in the fol-' lowin manner: When t e connection is extende to the connector, its liner'elay 145 becomes energized in.the same manner as the line relays95 and 620i the selectors F and E. The relay 145, upon energizing,

completes a circuit extending from ground G through the springs 151 and152' and slow acting relay 154 to the battery lead-74. The relay 154, upon energizing,- completes a circuit from ground G through springs 115 and 116, conductor 117, private wiper 118 of selector F (Ei 1), side switch-wiper 119, conductor 210 mm which one branch extends through t e relay 114 to battery, while another branch extends to and throu h the relay 98'of'-.the selector E and also t rou h the holding winding 17 of the line switc C to batterg'; When thecallin su scriber operates his calling device for t 'e third di it 2, the circuit of the connector line re ay is broken twice momentarily. Each time the relay. 145 deenergizes, a circuit is closed extending from ground Gr throughthe sprin 151 and 156, 160 and 161 sthe slow acting re ay I54'remaining operate during the entire time the relay 145 is operating), the vertical magnet 107, side switch wiper 162 and private magnet relay 163 to the battery lead; The vertical magnet 107 receives two impulses over this circuit and opterats in response. thereto to raise the aha wipers 104, 105 and 103 two steps. The private ma et relay'163 is energized by the first impu se to the vertical magnet and, being a slow acting rclay, remains in its energized position lmtil the last impulse is transmitted. In its'cnergizcd circuit rom ground (1" through springs position, the relay 1,63 completes a a 164 and 165 and private magnet 108 to the battery lead. \Vhen the private magnet relay 163 denergizes after the last impulse is delivered to the vertical magnet, it allows the rivate magnet 108 to dencrgize also, whici causes the side switch to be tripped to second position. The side switch wiper 162, in passing from first to second position, transfers the battery connection from the vertical magnet 107 to the rotary magnet 106. Now, each time the line relay 145 deenergizes in response to the operation of the substation calling device for the last digit 0, the rotary magnet 106 is ener ized over a circuit extendin from groun G" through springs 151 an 153, 160 and 161, magnet 106, springs 166 and 167, side switch wi er 162 and rela 163 to battery. Since the last digit is 0, t a rotary magnet receives ten impulses, thus causing the wipers to be rotated ten ste s onto the contacts of the desired line, 0. 2220. The private magnet relay 163 is energized in series with the rotar magnet and remains in its operated position until after the last impulse has been delivered. The private magnet 108 is thus energized as soon as the rotary magnet be ins to operate, and deenergizes shortly 9. er the wipers have been rotated onto the called line. This operation of the private magnet causes the side switch to pass from second to third position in the usual manner, thereby completing the connection from the calling to the called substation through the medium of its wipers 168 and 169. The side switch wiper 170, in

its third position, provides an energizing circuit for the cut-off winding 194 of the line switch C, and a guarding potential for the connector private bank contacts of the called line, extending from ground G through said wiper 170, springs 171 and 172, private wiper 105, thence to the connector private bank contacts and over conductor 173 and through winding 194 to battery.

The winding 194, u on energizing, attracts the armature 195, w ich operates to disconnect the line switch 0' from the called line.

and to complete a connection from the connector bank contact 196 to .the line conductor 185.

The side switch wiper 162, in passing to third position, com letes a circuit extending from ground through the interrupter 174, springs 175 and 176, ringer relay 110, side switch wiper 162 and relay 168 to battery. The relay 110 is intermittently energized over this circuit, each time operating to disconnect the calling from the called line and connect the ringer generator M with the called line. Rin 'n current then flows from one termina 0 said nerator through the ringer relay sprin 77 and 178, si e switch wiper168, sha t wiper '108, springs 188 and 184, line 185,

ringer 186, springs 187 and 188, line 189, wipers 104 and 169 and springs 181 and 180 back to the generator M. When the called subscriber removes his receiver from the switch hook, or as soon thereafter as the ringer relay 110 deenergizes, a circuit is completed extending from ground G through the side switch wiper 170, lower winding of the connector back bridge relay 111, ringer relay springs 182 and- 181, thence over the heavy conductor to the hook switch spring 188 at, the substation,.spring 190, t ence through the transmitter and receiver back over the other side of the line to and through the ringer relay springs 178 and 179 and the up r winding of the connector back bridge rdll iy 111 to battery lead 74. This circuit supplies the called substation with talking battery current and also causes connector relay 111 to energize. The relay 111, upon energizing,- byso arating the springs 175 and 176, opens t e circuit of t e ringer rela 110 so that the generator will not be again connected with the called line-after the receiver has been removed from the switch hook at the substation A. The two subscribers may now carry on an uninterrupted conversation over the talking circuit which is outlined by heavy lines in Figs. 1 and 2, the calling substation being 95 supplied with talking current through the connector line relay 145, while the called substation receives talking current through the relay 111, as described. The release 1" all of the central station apparatus is rought about by the hanging up of the receiver at the calling substation when the conversation is completed. The hanging up of the receiver destroys the energizing circuit of the connector line relay 145 by the separation of the hook switch springs 211 and 212. The relay 145 upon deiinergizing, breaks the energizing circuit of the'connector release relay 154.. The relay 154 thereupon definergizes and, by permitting the spring 160 to en age spring 191, comletes a circuit for t 0 release magnet 109. his circuit extends from ground G through the springs 151 and '153, 160 and 191, magnet 109 and springs 192 and 193 to battery. The magnet 109, upon energizing, immediately restores the mechanism of the connector ,to normal position. When the connector shaft reaches its lowest position, it separates the springs 192 and 193, thereby a lowin the magnet 109 to deenergize. The eener 'zation of the' relay 145. also disconnects e ground from the trunk release conductor 117, which ermits the relays 114 and 98 and the winding 17 of the switches F, E and C, respectivel', to detinergize. The de iergization of t e winding 17 permits the, lunger of the line switch C to be restored to normal position. The deenergization of the relay 120 1 whenever'a line lS- busy there is a guardthrough its lower winding, and operates ,in conjunction with the magnet 108 and the 98 ot the selectorE completes a -circuitfextending from ground G? t rough the springs 78 and 80, 87 and 197 198 and 199, 57 and 58 and magnet, 56 to battery. T he-magiiet 56, upon deenergizin immediately releases the selector file deenergization of the relay 114 causes .the release of the se- .lector B 'in the same manner as just. de scribed for the vselectorE when its, relay 98 selectors reach their lowest positions, the cir-' cuits of their respective release magnets are broken in the same manner as described forthe connector, and all apparatus em iloyed in the connection isleft in readiness or an-- other call In the foregoing description it was assumedthat the line of the called substation 'A' was idle when called by the subscriber at substation A. In case this line had been busy, the connector B would not have completed connection therewith and the calling subscriber would have been given-the busy signal in the following manner: It is evident from the previous description that ing ground potential u on its connector private bank contacts. T as it will be seen that at the instant the wipers of the connector L arerotated onto the contacts of a busy line, a ground connection is extended from the guarded private bank contact of said line through the wiper 105, springs 172 and 171, lower winding of the relay 111, ringer relay s rings 182 and 181, side switch wiper 169 (w iich is then in second position) to the sprin 200 of the relay 163. As the relay 163 den'ergizes after the last impulse for-the last digit has been delivered, the spring 165 engages the spring 200 before it is disengaged from the spring 164, and

l the private magnet 108 does not-deenergize, but remains locked in series with the lower winding of the back-bridge relay 111. The relay 111 also becomes operatively energized relay 163 to complete a circuit extending from'ground G throii h the springs 164 and 201, 202 and 203,,rc av 204 and springs 205 and 200m battery. The relay-204, upon energizing, disconnects the private wiper from the magnets 111-and 108 and substitutes therefor the ground G". This prevents the private magnet from dei nergizing and completing the connection with the called line in cascthe guarding potential should l)e'rcinov d' froni its private bank contacts before ,tlieQconncctor is released. The relay 204. in its'e'n'ergizccl position. also 1 completes a circuit over which the callin" subscriber receives the busy signal.. This circuit extends from one teruiuial of the busy i i alln machine N tnrough springs 207 in 20s 0 relay 904, contact 'point 20,

deenergized. When the switch shafts of the side switch wiper 168, thence over the heavy .condiictors to and through substation A and back over the other side of the line, to and through the connector line relay 145 to ground G, thence through the battery B tothe battery lead 74 and to tlie other-terminal of the busy signaling machine. Since the private magnet'is not allowed to describer, by hanging up his receiver, may release all-of the switches in the same manner as when a successful connection has been made.

In the foregoing it has been explained howa calling subscriber may obtain connection with any other subscriber iii the system by operating his calling device for t e successive digits of the number of the line wanted. It will now be explained how, in case of eiiiergcncv, a subscriber may ob'- tain connection with an operator without operating his calling deviccat all. It will be remembered that, when the calling sub-' scriber removes his receiver, the line switch C operates to extend the connection to the first selector E, whereupon its line relay 62 becomes energized over a circuitwhich includes the transmitter of the substation A and the lower winding of the relay 136. This circuit, therefore, furnishes the calling substation with talking battery current and also causes the relaylilti to energize. The energization of this relay completes the secondary circuit of the operators set'O. This circuit extends from one terminal of the secondary winding of the induction coil 129 totlie up er winding of relay 136, springs 127 an 128, 137 and 138 and rc-- ceiver 139 bacl to the coil 129. The .two windings of the relay 136 also form an iiiductive connection between the substation talking circuit and the secondary circuit of the operators set, whereby the calling subscriber may converse with the operati It will thus be seen that every calling subscriber is put into connection with the operator as soon as he removes the receiver to a bell. lamp or suitable signal in case it is A desired to provide an audible or visual signal to attract attention if there should be no one listening on the operators set who" a call comes in.

It will be seen therefore, that by-my invention I-prpvide an-arran out for ens bling an operatorto-listen 1n onall lines-as soon asthe. receivers at'the submit-1L tions thereof are removed from their switch 1 books, and inwhich means are providedjtor preventing the operator from listeningin on any calling lines over which thecalls-have progressed to the point where the notaryfl calling device has been operated toobntroh the automatic switches. Thuseach and, every calling line is momentarily connected "with the operators tele hone, regardless of the character of the "cal and if the calling subscriber wishes atanyitime'to converse with the operator no operation of the rotary calling device at the callingJsubstation Lie necessary. Each calling line is initially connected with the op'erators telephone, but the initial'operation of the first selector disconnects the operators telephone from the calling line, whereby the call may then progress in the usual manner, and without the possibility of the operator listening in on the connection. The operators telephone can be located at a manual.switchboard, or at any other suitable point in the system, and every calling subscriber can, fore operating the rotary calling device, attract the attention of the operator by simply speaking into the transmitter at the callingsubstation. This is useful, for example, in turning in fire alarms, or in conversing with" a trouble operator, or for various other purposes. Every call that goes through the exchange must make a passing connection, so to speak, with the operators' telephone. If the calling subscriber desires to converse with the operator, then thecall stops at that point. On the other hand, if the call is regular, and from one line to another, then the call immediately passes on and finds the called line. In every case, and when the calli and called lines are finally conn nectecl the operator is cut oil and cannot overhear the conversation. Thus, for certain purposes at least, anpperator is given supervision of the a stem without entailing any :additional 'wor oreflort on the part of the subscribers. A subscriber may at any time obtain the. attention -and services of an :operator,

at this does not necessitate any additio 1 devices at the substations.

\Vha I claim as my invention is:- 1. In a telephone system, a plurality of 'teleph one lines, mechanism operable under substation control to extendconnection from calling lines to called lines, and disconnect therefrom,a telephone common to all of said lines, means for connecting said telephone with a calling line,'andmeana controlled by the operation otsaid mechanism.

telephone lines, mechanism operable undersubstation control to extend connection from callin lines to called lines, and disconnect there rom, an operators board common to all of said lines, means for connecting said operators board with a calling line, and means controlled by the operation of said mechanism to always disconnect said opera- ;ors board before the call reaches the called 4. In a telephone system, a plurality of telephone lines, an automatic switch mechanism common to said lines, responsive to any calling arty to extend connection from the calling line, a telephone common to all of said lines, means for connecting said telephone with a calling line, and means controlled by the operation of said mechanism to always disconnect said telephone before the call reaches the called line.

5. In a telephone system, a plurality of telephone lines, an automatic switch mechanism common to' said lines, responsive to any calling arty to extend connection from the calling ine, a signal common to all of said lines, means for connecting said signal with a calling line, and means controlled b the operation of said mechanism to always disconnect said signal biefore the call reaches the called line.

6. In a telephone system, a plurality of telephone lines, an automatic switch mechanism common to said lines, rwponsive to any calling party to extend connection from the calling l1ne,-an operators board common to all of said lines, means for connecting said operators board with a calling line, and means controlledby the operation of. said mechanism to always disconnect said operators board before the call reaches the called line.

7. In a telephone system, a plurality of telephone lines, mechanism operable under substation control to extend connection from calli lines to called lines, and disconnect there rom, a telephone for connection with every calling line, common to all of said lines, and means controlled by the operation of said mechanism to always disconnect said telephone before the call reaches the called line, said mechanism comprising a first selector in which said means are pro anism common to said lines,

every calling line, common to all of said lines, and means controlled by the operation of said mechanism to always disconnect said signal before the-call reaches the called line, said mechanism comprlsing a, first selector in whichsaid means are provided in the form of contacts which control the circuit of said signal.

9. In a-telephone system, a plurality of telephone lines, vmechanism operable under substation control to extend connection from callinglinesto called'lines, and disconnecttherefrom, an operators board for connec tion with ever calling line, commonto all of said linesfand means controlled by the operation of said mechanism to always disconnect-said operators board before the call reachesthe calledline, said mechanism coinprising a tirstselecton-in 'which'said means are provided in the form of contacts which control the circuit of said operators board.

10. In a telephone system, a plurality of telephone lines, an automatic switch m'ecln anism eon'imon to said lines, "responsive to any calling party to extend connection from the calling li n'e, 'ate'lephone for. connection with every calling line. ommoir to all of said lines, and means controlled by the'operation ofsaidmechanism to'alwa disconnect said telephone' before the cail reaches the called line, said mechanism cou'iprising a first selector in which meansare vided inthe form of contacts which "control the circuit of said telephone. I y

11. In atelephone system, a plurality of telephone lines, an automatic switch 'meclr anism common to said lines, responsive to any calling party to exte'nd coimeciiou from the calling line, a signal for connection with every calling line, common to all of said lines, and means controlled by the operation of said mechanism to always disconnect said signal before the call reaches the. called line, said mechanism comprising a first selectorin which said means are provided in the form ofcontacts which control the circuit of said signal. 7 I

12. In a telephone systenna plurality of telephone-lines, an automatic. switch mechresponsive to any calling party to extend connection from the calling line, an operators board for connection with every calling line, common to all of said lines, and means controlled by the i are provided in the form of contacts which control the circuit of said operators board. 13. In a telephone system, a plurality of telephone lines, a telephone common to said lines, and means controllable from any calling substation to automatically connect the calling line with said telephone, and disconnect therefronaibet'ore the call reaches the called line.

1-1, In a telephone system, a plurality of telephone lines, a telephone common to said lines, said telephone being connected with all calliiig lines over which the calls have notiprogressed beyond a certain point, and

disconnected from all calling lines over which the calls have progressed beyond said point, said system being provided with means by which the said disconnection is controlled by the calling subscribers only.

15. In a telephone system, a plurality of telephone lines, a telephone common to said lines for the purpose of connection with all calling lines, means by which the removal. of the receiver at any calling substation connects the calling line with said telephone, a calling mechanism at the substation of each line, switches responsive to said mechanism to extend the call from any calling line, and means controlled by the operation oi said switches to disconnect the said telephone from the calling line before the call reaches the calledline. i

16. In a telephone system, a plurality of telephone lines.'a telephone coi'm'non to said lines, means whereby said telephone is operatively connected with all calling lines over which the calls have not progressed beyond a. certain point, and means whereby the said telephone is not in operative relation to any calling lines over which the calls have progressed beyond said point, said means beinguinder the control of the scribers only.

17. In a telephone system, a line. a telephone, a calling mechanism for said line. a hook switch for said line, means whereby the operation of saidhook switch connects calling subthe said line with said telephone, and means whereby the operation of said mechanism disconnects the telephone from saidline.

18. In a telephone systcn'i, a plurality of first selectors, a telephone common to said selectors, connected therewith, and means on each selector for opening the circuit of said telephone, said means being operated by the initial actuation of said selectors. 19. In a telephone system, a plurality of telephone lines, automatic switches controllable over said lines to extend calls there from, an operators telephone for'listening in on all calling lines, and means controlled by said selectorsfor preventing listening'in after the operation thereof.

20. In a telephone system, a' calling line, a calling mechanism therefor, means respon-.

sive to said mechanism for extending the mon to a plurality of said lines, a line relay for said switch, a second relay connected in series wit-h said'line relay and adapted to be energized in series therewith, and an operators telephone set adapted to be con nceted throughsaid switch to a subscriber's line upon the energization of said second relay.

22. Ina telephone system, a plurality of telephone lines, an automatic switch common to a plurality of said lines, a line relay for said switch,'a second relay connected in series with said line relay and adapted to be energized in series therewith, an operators telephone set adapted to be connected through said switch to a subscribers line upon the energization of said second relay, and normal contacts controlled by the movement of said switch for again disconnecting said operators telephone set.

23. In a telephone system, a plurality of subscribers lines, an automatic switch common to a. plurality of said lines having vertical and rotary motion, an operators set normally disconnected from said switch, a line relay for said switch, a" second relay adapted to be energized in series with said line nelay for connecting said operators set with said switch, and ofi -normal contacts in the circuit of said operators set adapted to be opened by the first vertical movement of said switch for again disconnecting said telephone set from the switch.

.24. In a telephone system, a plurality of subscribers lines, an automatic switch common to a plurality of said lines, an operators set normally disconnected fromsaid said switch, a douhle-u'mmd rela for said switch, a second double-wound re ay having one winding connected in series with one of the windings of said line relay, the second winding of said second relay being'connected in series with said operators telephone, means for energizing said line relay and said second relay when saidswitch is seized to. connect said operators set with said switch, and contacts connected in series with said operators telephone controlled by the first movement of said switch to again disconnect said telephone from said switch.

In a telephone system, a-plurality of telephone lines, a telephone common to said lines, means controllable from any calling substation to auton'iatically connect .the call-- ing line with said telephone, and disconnect therefrom, before the call reaches the called line, and means for preventing connection. of said telephone with called lines.

26. In a telephone system, a plurality of telephone lines, a tele hone common to said lines, said telephone heing connected with all calling lines over which .the calls have not progressed beyond a certain oint, and disconnected from all callin v 'nes over which the calls have progresse' beyond said point, said system being rovided with means by which thesaid disconnection is controlled by the calling subscribers only, and means for preventing connection of sand telephone with called line's.

Signed byme at (Chicago, county, Illinois, this 15th day of'April, 1911.

ALEXANDER E. KEITHL 'Witnesses:

A rmen J. RAY, i E.'.D. Fangs.

Images