US1553369A - Telephone-exchange system - Google Patents

Description

Sept. 15. 1925. I

. J. F. DAHL TELEPHONE EXCHANGE SYSTEM Filed Fe b. 9,; 1925 nwk \ muozum UOELO 1,553,369} J. F. DAHL TELEPHONE momma SYSTEM Filed Feb. 9, 1923 2 sheets-sheer 2 Sept. 15, 1925.

llarymz/ lrwmfok: Jack EDqh/.

Patented Sept. 15, 1925.

COMPANY, INCORPORATED; OF NEW YUBK, N-l

TEL'EPHON n oonroimrrdn or' n rw YO K? HANGE S YSTEMi-f To all 'LlJ/LOWZ, it may concern; V

Be-it known that I, JAQK Fv D L, ,a: citizen of the: Unitecl=-; States, ,resijdinge att East Ora ngein the county of Es'semystatee ofNewfJersey, have invented certaiili neww and useful; Improvements. in a Telephone Exchange ;Systems,;' of; which j'the following is a full, clear, concise,v Land itexact descrt s tionz This invention relateskto ya telephQne :exchange system and :more particularly. to; a system in; which operatorsar'e employedaforw extendingq connections incoming: to; their positions fIOlYlu ofices having machinei switching equipment.

In systems of thischaracter it .iskfoundr; desirable that the: manual: operators :be: given a: the ainiormation' irequired ifo'ri athemsto" ex tend i [or complete conner-i-tions,'- without; the v necessity of, communicating sorally, with the L calling subscriber in the machinewswitching office or with other operators. To "this: end, i each operators position {in the :manua'laoffice is provided with call indicating .mechanism'n includinga set ofnumber: indicating devices; which@isuoperated automatically under theu control 1 of registering mechanism in the mien: chine switching otfice to inform theamanua l" operator of the number:and :characteri-"ofw the trequired Iconnectiom- IhJlSwC-HStOIIIHII'y in 1 arrangements of this character to provide each trunk circuit incomingitoianaoper atoris position; from: a distant: machine switching iotiice .With a signaL lamp, 'the=.illumination ofwwhich' advises the operator that ,a call is aWaitingt-her' attention; on s the: corresponding;trunk.v At her convenience, shewassociates 'thc calling; :trunk with "the 5: common indicating .mechanism at :her ipOSl tionz-and thereupon the wantedadesignation is set up and i displayed before the operator who n-proceeds to complete the connection: here. nocparticular attemptis made to set ecure uniformity .in the distribution ofs calls before the :several voperators in i an ofiice: of this? characterit may fre'quentlyioccur dur-, ing busy hours of the day that an excessive number} of calls simultaneouslyappear ion the trunks at any givemoperatofs position, while :at: the: two positions :adjacent' thereto only comparatively few calls are awaiting. attention. In order that the'completion' "of callsnshalll not be unduly. delayed'k'on this account,provision ism-adewhereby the adj a cent operator at either side of a home opera- 'a seco'ndacall' is; awaiting tor s position mayaassi st :thehome'i operator 1 by attending-tm some 'of' the calls-awaiting: attention at Eher 1 position.

When ieither operator attends to a waiting; calla. she tope'rate's a display key to associate thez tr-unki-z circuit upon? which i e the *i call is:

iqwming with her owlr indicator mecha 1118mm Thus-, eachi operator'ihas two groups of display keys, oneagrfoup comprising keys individual to each of the-trunkcireuits non mallyr incoming :to-herown" position and the-otherqgroupg comprising keys individual to such; trunks for the A use of the operators on either-side:ofher position then any display key is operated; I the aforementioned sign-ah lamp of the-corresponding: trunk circuit-is distinctively lighted to:indi'cate-to the operator; who: has assumed theiresponsibility for extending the requlired connection; that therdesignation of tlievreq'ui-red connection is aboututo be displayed onpher indicator.

An efiieient operator notin-g the distinctive ligh'tingof an assignment lampiwill takeup the plug of: the corresponding trunk circuit" with! =one :hand and extend t the connection to the desired wline f multiple ras soon as the line designation becomes displayed-and F will, with herother handlwhile making such 1 con neetion, depress .the' display keyfof another trunk circuit of her positioin' upon which :attention, on if she hast-no other waiting; call and the operator of an iadjacentvpositionx:is overloaded, she willreacli'overnnd depress an adjacent or 3 team worlr idisplay key of one of the trunkcircuits of such 1 adjacent! position 1 upon which a ca1l1 isswawaiting attention. Thus, I at the same: instant; 4 the designations of two i i lines, the "calls" for which: have originated" upon; trunk circuits. incomingv to one-iop'e-ra toris positionfmay f-be idisplayed, one on the a home operator s :inclicatonand the' other uponwan adjacent op'erators indicatorz In such case, the assignment damp of each 3 of thentwotr unkcircuits will be lig h teii; andunless ssome r diiference is made in I th man ner in which these:lampsarelighted', t-heltwooperators :will not know to which trunk the displayednumber relates-5 For thi's purpose, when an :1 assignmentwis m ade byfj the home operator; the lamp: of the" assignedftrunk circuit of her position is 'flashedat a slo w rate,::while :if' the: assignment is made by adjacentzi-operator ithel lamp-iis flashed at a faster rate. 1

To economize in the equipment of the manual ofiice, it is proposed to employ the busy back and peremptory interrupters of the ringing machine, the former for flash ing the assignment lamps slowly and the latter for flashing them at a faster rate. Since the peremptory interrupter is connected to battery, it becomes necessary to interpose a relay between the interrupter and the, flashing circuits of the assignment lamps in order to supply interrupted ground potential ,to these circuits. As the oifice must remain in service twenty-four hours of each day, this relay would be in constant operation unless some provision were made to relieve it. Further, since the busy baclr interrupter must perform its other usual functions in the office to which it is assigned, it is essential thatno load be added to it which may at any instant be so great as to burn out its contacts as might happen if a lamp at each position of the ofIice were connected 'to the interrupter at the same instant. Again, the interrupter must be protected against being rendered ineffective through the accidental grounding of one of the lamp circuits. If, then, the operators positions of the office are divided into groups and provision is made for associating the interrupters with the lamps of only 7 the groups of positions in which calls are being displayed, and further provision is made for overlapping the groups for enabling the lamps of adjacent positions to be operated when a trunk circuit is assigned by an adjacent operator, the foregoing difficulties will be largely obviated.

It is, therefore, an object of this invention to provide improved means for associating interrupter mechanism with groups of operators positions.

This and other features of the invention will more clearly appear from a consideration of the accompanying drawings and appended claims. Fig. 1 shows diagrammatically in the upper portion'thereof a subscribers line terminating in a machine switching oifice and such switching mechanism of the Office as is necessary to extend connections from such line to trunk circuits extending to other manual offices of the exchange area. In the right portion of this figure, a portion of a'manual operators call indicator is disclosed and in the lower portion thereof, the mechanism of three groups of operators positions is disclosed for associating the interrupters shown at the left of the figure with such positions.

Fig. 2 shows a trunk circuit incoming from the machineswitching office shown in Fig. 1 arranged to extend connections to subscribers lines, one of which is shown at the right of this figure.

The apparatus shown in the upper portion of Fig. 1 for extending connections Scudder, 1,395,977, issued November 1, 1921. Y

The trunk circuit shown in Fig. 2 and that portion of the indicator mechanism of the operators position associated with the trunk circuit and shown in the right portion of Fig. 1, are of substantially the same type, as fully disclosed in the Patent 1,464,084, issued August 7, 1923, to A. E.

Lundell and E. H. Clark, and reference may be had to such patent for a complete disclosure of circuits of this character.

In the lower left corner of Fig. 1, two interrupters 107 and 108 are disclosed. These interrupters are both operated from the ringing machine of the manual office Y, interrupter 107 being the usual busy back interrupter and 108 the usual peremptory interrupter. The operators positions of the office Y aredivided into groups, each group comprising eight positions and each group having relay equipment associated therewith for controlling the connection of the interrupters 107 and 108 with the flashing circuits of the assignment lamps of all trunk circuits of the positions of the group. In Fig. 1, the relay equipment of three such groups of positions has been disclosed in the three rectangles indicated by the dot and dash lines, these groups being the first, an intermediate and the last groups. The indicator mechanism fragmentarily disclosed, is shown as belonging'to operators position No. 1 of the first group.

Briefly, should the operator at any one of-the first seven positions of the first group assign her individual indicator to a trunk circuit, relay 111 will operate in turn operating relays 114 and 115 to associate the interrupters 107 and 108 with all of the flashing circuits of assignment lamps of the eight positions of the group. Should either the operator at the eighth position of the first group or the operator at the first position of the second group, which, for convenience, may be assumed to be the intermediate group illustrated, assigns her indioator to a trunk circuit, relay 116 will operate in turn operating relays 114 and 115 of the first group and relays 117 and 118 of the second group to associate the interrupters with all of the flashing circuits of the assignment lamps of the first and second groups. Should the operator at any of the positions 2 to 7, inclusive, ofthe second I ,ratus and the manner ,otlice senden110f As soon, as

cuit 105 106 incoming to [the c.1105, inner nost upper mew cuit, relay 119 willoperate inturn operat: ing rel'aysf117 and 118 for associating the, interru'pters with the flashing circuits ct the assignment lamps associated with the ratorsi positions of the second group. Siinilarly, the connection ofithejinterrupters is Cant-louse by the remaining intermediate and last groups of operators positions,

Haying new briefly described the appain which it functions, it is thought that the invention, will be more clearly understood from adetailed descriptionithereo fl 1 It willhtliere fore, be; assumed that the subscriber A whose lineterininates in theanachine switching, ofiice, X desires aconnection with a subscriberll whose lin e terin 'nates in the manual office Y, The calling subscr ber A, to ;in t ate the call,

removes his recei er frorn. itss it chhook} v ,anclthrough theoperation of thelineswitch fobtain s a c'onnectionfoyer the brusliesg of this switch; and the lower contaets of cams 101 and 102 ,o f the sequence switch; of the district selector 150, withlthe central i v i the central office sender is connected withithe calling, line, the usual dial tone is transmitted and the calling subscriber; thereupon proceeds to dial; the several digitsof thedesignationw cof th'etdesired lineB Theregisters. of the oifice sender record the several digits dialed by the subscribenand, in .the, well known manner, the sender then proceeds to control thesetting of the cli strictfselector 150and {the oflice selector175 in. accordance with the,

office; designation e of the desired line, In the presente case, it is assurnedjthat. the brushesio f the ofl ice selector 17;5 are posi-v tionedj upon the rterininals of a trunk ciroffice Y,

Upon the seizure of the trunk. circuit,

-106, a circuit becomes established for the trunk'a'elay'200 which. maybe traced in part from ground, through the left wind-v ing ,of relay 200, the left normal contact of relay 201, "the lower left winding of repeating coil 202, conductor 203, the,innermost lower arinatures and back contacts of relays 2041' and 205, conductor 106,] lower brushes of switches 1 r 5 and 150,] lower contact tot earn 104, through the controlling circuit of the office sender, returning ,over the lower contact of cam 103,. the upper. brushes of switches V150, and 17 5, conductor ar natures andback, contacts of relays 205 andfl 204, conductor- 208', upper left winding of repeating ,coil 202, righthorinal contact of relay 1 201 to battery through'the rightiwindinglof relay 200. At the oifice, sencler,..upoi1 the closure.

corded upon a Icalhindicator,

At :the trunk circuit, relay 200; upon eners gizing closes a circuit for relay 209 which may be traced; from battery; at the outer. right armature and, back. contact of relay 210,:W inding of relay 2O9, the,right armature and back contact of relay 212 to grcund at, the armature and contact 0;fi relayc200. Relay 209,. upon, energizing, closes a locking circuit for itself extending fl01l1j,btlt; tery through ,its ,outer, iright armature and contact, itswinding, and lto ground at the; armature and ,contactof -elay 200 ',and, at its inner ri ght arniature and front contact, establishes ,a. circuit for the assignment; lamp, 213. This circuit inay be, traced from-bate tery, through lamp 213,, tive Winding of relay;214 ,,the inner right; armature and front contact of relay209; 130;, ground The hence operator, it,}being;1 assumed that sheis free at this illlllQ'ilO, attend; to this calLnoting-the illumination of lain n 213, depresses the home display key 211;; associated with the trunlrcircuit correspond ing to the lighted la1np 213- whereupon a1 he it l enduce V circuit is established for the assigninent e andibackcontact of relay 21''!- conductor 218,1

the right winding of relay 215,-:the outer left 4 armature andgfrone co itaeto relay; 209,the,

lower contact of lrey 211, conductor-243, the

armature and baclncontact got, relay 125 to ground at the right armature and, backicon 1 tact of relay 120,, Relays 123,; gize in this circuit Relay 2115, upon energiz ing,,closes 1a lock- 7 ing circuit for itself extending from lbattery on conductor 2l8through both of its wind: ingsgto ground at thei frontigcontaet of its. innei dleftarmature and also closes anhobs viouscircuit for relay 210.; 1 Relay 210, upon energizing, opensatgthe back contact of its outer right,ar nature the initial energizing circuit of relay 20 9, and closes a circuitforv relay 214 Whichunaybe traced, from ground through the right, winding ofrelay21-4e, the, inner aight armature and front contact of} relay 210 .to battery at the outer right ar1n a-..v ture. and contact-ofarelay'209: Relay 210- also, prepares a flashingcircuit for the lanip 213 fwhich: later becomes. effective followingf the deenergization of relay 209. With relays 21 1 and215 now. energized, zacircuit is closedfor relay 205 whichinay be traced from battery, through-the left armature and l and 21.5 ,enern z contact ofirelay 21 4,c0nductor 219, winding Relays 205 and 125 energize; in this circuit;

relay 205 disconnectlng the .wvindings e of trunk relay ,200 from the trunk iconductors 105 and 106, and extending these conductors over conductor-S206 and 207, through the windings of control relays 120, 121 and 122 of the call indicator of the operators position in which the trunk circuit 105106 terminates.

Upon the disconnection of the windings of relay 200, following the energization of relay 205, the locking circuit of relay 209 is opened and relay 209 deenergizes opening the previously traced circuit of lamp 213. Relay 214 upon energizing closed a locking circuit for itself extending from ground through its right winding, its inner right armature and front contact tobattery through the winding of relay 212, but relay 212 did not energize in this locking circuit as long as relay 209 remained energized since it was shunted by direct connection to battery through the outer right armature and contact of relay 209. With relay 209 now deenergized, however, relay 212 energizes in the holding circuit of relay 214 and at its right armature and back contact opens the initial energizing circuit of relay 209.

At the call indicator shown fragmentarily in Fig. 1, upon the energization of relay 123 thereof, holding ground was connected to conductor 124 through the outer left armature and back contact of relay127 and through the left armature and front contact of relay 123 for holding the various switching and registering relays (not shown) of the indicator in their operated positions as soon as they are energized by the control relays 120, 121 and 122 in response to code impulses transmitted from the ofiice sender 110. Ground on conductor 124 is also furnished to the armatures of the control relays for controlling the various operating functions of the call indicator. At its right armature and front contact, relay 123 connects ground to conductor 109, thence through the winding of relay 111 to battery. It will be noted that relay 111 is common to the first seven call indicators of the first seven operators positions comprising the first group of positions. With relay 111 energized, a circuit is established for intermittently operating relay 114 which may be traced from battery through the winding of relay 114, upper armature and contact of relay 111, conductor 128 to ground through the busy back interrupter 107. A circuit is also established for intermittently operating relay 115 which may be traced from ground through the winding of relay 115, the lower armature and contact of relay 111, conductor 129, to battery through the peremptory interrupter 108.

With relays 114 and 115 both operating intermittently at difierent rates under the control of the interrupters 107 and 108, ground potential is supplied intermittently to all of the flashing leads corresponding to the leads 112 and 113 extending to all trunk circuits.terminating in the first eight operators positions comprising the first group of positions. Since it has been assumed that the home operator has attended to the call incoming on trunk circuit 105106, relay 221 is at this time unoperated and, therefore, with relay 209 deenergized a circuit is established for flashing the assignment lamp 213 of this trunk circuit at a slow rate to indicate to the home operator that a line designation is being registered upon her indicator and that the call so being registered will later require her attention. The circuit for lamp 213 may now be traced from battery through the lamp 213, the left noninductive winding of relay 214, the inner right armature, and back contact of relay 209, the left armature and front contact of relay 210, lower armature and back contact of relay 221, conductor 113, the upper armature and contact of relay 114 to ground. The intermittent operation of relay 115 is at this time ineffective, unless an operator at some other position of the group has assigned a trunk to her indicator on a team work basis.

In response to code impulses transmitted from the office sender 110 in accordance with the numerical designation recorded upon the registers thereof, the indicator at the operators position functions to register the several digits of the line designation, following which the line designation becomes displayed upon the indicator.

During the transmission of the code impulses and following the setting of the stations relays of the indicator, ground potential is connected to the ringing selection conductors 244 and 245, it being assumed that the party on the called line is desired. Upon the connection of ground potential to conductor 244, a circuit is established over this conductor, upper armature and contact of relay 205, conductor 237 to battery through the winding of relay 233. This relay, upon operating, locks through its winding and its lowermost armature and contact to ground at the inner left armature and front contact of relay 212. Ground potential connected to conductor 245 causes the operation of relay 232 over a circuit which may be traced in part from conductor 245, lower armature and front contact of relay 205, conductor 238 to battery through the winding of relay 232. Relay 232 upon energizing locks through its lower armature and contact to ground at the inner left armature and contact of relay212.

When the code impulses have all been received from the ofiice sender 110, relay 126 becomes energized. These operations have not been described in detail herein since they form no essential part of this invention and since they are fully described in the patent I of (llarlr her'eiiibefore referred to. Relay 126 nponener'gizing opens the-"previously traced ,circuit e'znt'eiiplthrouglitlie windings of relays 125' and 205, therebycausing the release ofthe'se relays. Relay 205, ri1)oii"deei;1ei'gizing, disconnects C0nductors206 and 207 from the trunk conductors 105"aiid1106,and 'recoiinects the trunk conductors 'ivitlfthe windings of trunk .relay:200., Relay 200 now becomes energized over" thepreviously traced circuit extending to the ofli'ce; sender, "whereupon 'thefifiice sender, having iperforine'd; all of the functions' required of it, is dissociated from the connection. .Thefitalking circuit is now es tablished from the calling line over the upper contacts of caiiis 1 0 1 to104, inclusive, and tliehrushes ofswvitclies 150 and 175 to the trunk conductors 105' and 106, and relay 200, is held. energized tliereoven A new holding circuit is znow establislied for relay 212,,Wl1l0l1 may be. traced from battery through the right armature and front con tact of relay 212 to .groun'diat' the armature and contact of relay 200 in shunt of, the Winding of relay. 214E. Relay 214 thereupon deenergizes opening at. itsleft' ZL11I1EL CL 1I62L11d contact the initial energizing circuit of relay205. J. m p l {The operator, noting the illumination of the lamps ofthe indicator, takes up the plug 228 of the trunk circuit designated by theflashing'la np213 and [tests the sleeveoi v jack 227 tOIdGtBI'lIilIle if tlie desired line is idle,;and;,upon"finding=it idle, inserts the plug in, the i j ack Upon? the insertion of the plugintlie jaclgfsleeve relay 217 is-e'nergiz'ed ina circuit which mayzbetraced from batterythrouglr the Wiiidinguof ringing relay 2 7 :Y ght armature and baelrcontact ofrelay 2 29, armature andback contact of relay 230,0uter leftarniature and contact of relay 212, outer rightrarmature and back contact of relay214, winding of relay 217 sleeve of plug ,223, sleeve,-of jack. 227 to ground through the gout ofi relay246 of the called line. ,Lanip 224 being shunted-by thevvindng f ay228 tin ie. Relays246 .and 217 energize in this circuit relay 217 disconnecting the tip of plug 223 from conductor, 226 which extends through the upper armature of relay 221 to the test ivinding of the operators head set,

nnd connecting" the tip of the plug to the uppe r. ,;arrnature of the ringing ,relayz228. Relay at its lower armature, and back Contact, opens-the holding; circuit previously traced through the windings 0f prelays 21 5 i ,andp123, whereupon-these relays deenergize,

relay disconnecting gnound ,1' potential from the holding conductor 124, thus releasand extinguishingthe lighted lamps. Relay 123 also ren oves ground potential "from conductor'109 releasing relays 11,1, ll i and. 11.5,

in-coining to sueh does not energize at this 'shunted norv deenergi has an indicator assi'giied totrnnh circuits 'Wasi flashedis opened "and the lai rip is exringing current to called line; I Withfre- 121 3 9217 and; 233 energized, a eircuit is estate were may; 2 15, ri e v deei'iergi'zingjopens the blIQttlt, of a la 21 0 an' li'elreupon the circuit over 'vvhrclrlan p 213 arn'i'at'ure and team of relay 212, Belay 241 upon energizing locks the alternate emitter of; its right armature, over the circuit; previously traced to,ground at the innenleftarniaturejof relay2l2. With relays 228, 232, 238 an d 24:1 energized the are culit, over which curr'entfrom the source'239 is applied to the .calleddine, may, be traced from thesource 239,, the right inding of marginal relay 230, the, upper armature and fi'Ol'ltjp dlit a dt of relay 232, the left armature and contact of relay 211,, the innermost lo'v'ver armature contact of relay 233, the upper armature l and front contact of ring: rel'ayf22'8, the upper armature and front contact of relay 217,: tip of plugt223, tip of jack 227;.the h ell 242at the substation of the desired"linje, r ng of jack ring of plug 223, loiver'arinature andfront contact of re lay 228 to ground at the v innermost upper arinature' and frontcontaet of relay 233. c

'Inres'porise to theringingiof bell 242, the called 'snbscriher irernoves his receiver from "its "svvitclihook, whereupon marginal relay "230 'becjoir es' energized and at ,its armature and contact'bpens the shun t around um winding efgreia 29. Relay 229. ne energizes in ,series yithi'elay 228 a'nd at its right arinatiire and front contact closes a"-l'ockin'g circuit forpitself and f0r,;relays 246Qand 217*in; shunt ofthef Winding, of iflee r l y '2 Thi w fw t matt ture and tempt ofrelay 2l2, the outer right armature baclccontact of relay 214,,the of relay 217 sleeve contactsiof plug winding 7 223 {and jack 227 togroundthrough the Winding ,o'r jiei y 246. ltelay 2 28, ,beiiig e s, disconnectii'ig the source "or; ringing current "23 9 it'ro nthe conductors of thecalled line ancl connecting I 'the' icon ductors of the calledlineto the right ing allenergized relays of the call indicator windings of repeating coil 202 hrwghthe WlIlCl'll'lg of supervisory relay 285, cult is now established for the supervisory non-grounded pole of battery, the lower right winding of repeating coil 202,. winding of relay 236, the lower armature and back contact of relay 228, ring of plug223, ring of jack 227, through the substation of subscriber B, tip of jack 227, tip of plug 223, upper armature and front contact of sleeve relay 217 upper armature and back contact of relay 228 to ground through the upper right winding of repeating coil 202. Relay236, upon energizing, closes a circuit for reversing-relay 201 which may be traced from battery, through the winding of relay 201, armature and contact of relay 236 to ground at the left armature and contact of relay 229. Relay 201, upon energizing, reverses the connection bet-ween the windingsof trunk relay 200 and conductors 105 and 106 of the trunk circuit for supervisory purposes.

Upon the termination of the conversation, the subscribers A and B will restoretheir receivers to their respective switchhooks whereupon the apparatus at the machine switching oliice X restores in the well known manner and the previously traced circuits of relays 200 and 236 will be opened. Relay 200, upon deenergizing, opens theholding circuit ofrelay 212, which, inlturn, opens the locking circuits of relays 232, 233 and 241 and opens the previously traced holding circuit extending through the windings of relays229, 217 and246. A. circuit is noW effective for the disconnect lamp 224 which may be traced from battery through lamp 224,the winding of r elay 217, sleeve contacts of plug .223 and jack 227 toground throughthe winding of cutofi relay 246.

The operator, noting the illumination of the disconnect. la'mp224, removes the plug 223 from jack 227, whereupon relays 217 and 246 release. All apparatus ofthe trunk circuit employed in establishing the connection is now in normal condition.

Had the home operator been busy at the timethe call came in upon the trunk circuit 105106 of her position and the adjacent operator been free, the adjacent operator would have reached over and depressed the team work display key 225 corresponding to the trunk circuit the assignment lamp 213 I of which was lighted. Upon the depression 210 and at its outer left armatureand contact closes a circuit for relays 204 and 221 and a relay of the adjacent operators i ndicator corresponding to relay 125 over a circuit which maybe traced from ground at the adjacent operators indicator through the relay corresponding to relay 125, conductor 249, the outer left armature and front contact of relay 222, the upper winding of relay 221, winding of relay 204, left armature and contact'0frelay214-to batteryas soon as relay 214 becomes energized following the energization ofrelay 210.

Relay 221 upon energizing locks from battery through its lower winding and inter mediate armature and contact to ground at the inner left armature and front contact of relay 212. Relay 212 becomes energized in the holding'circuit of relay 214' following the energization of relay 210 and the deenergization of relay 209, in the manner previously described. -With relay 204 energized, the conductors of trunk circuit 105 106 become connected through the innermost armatures and front contacts of relay 204 to conductors of the group 234 leading to the indicator mechanism of the adjacent operators position. Upon' the energization of relay 204, relay 200 becomes deenergized. The assignment lamp 213 is now' disconnected from ground at thein er right armature and front contact of relay 209. i J When the adjacent operators indicator was assigned to the trunk circuit 105-106,.

it being assumed that the adjacent operator is at position2 of the first group, ground potential was connected to the conductor 109.

causing the operationof relays 111', 114 and 115, previously described, When, therefore, relay 209 deenergize's,'a circuit is es-v tablished for repeatedly flashing the lamp 213 which may be traced from battery through the lamp 213, thenon-inductive winding ofrelay 214, the inner right armature. and back contact of relay 209, the left armature and front contact of relay 210,

the lowermost armature and front contact. of relay 221, conductor 112, the upper armature and front contact of relay 115 to ground. It will be recalled that relay 115 is operatedintermittently following the energization of relay 111 under the control of the. peremptory interrupter 108. The lamp 213 continues to flash at a fast rate until the adjacent opera-tor, seeing the display of. the required line designation upon her indicator, proceeds to extend the connection reaching over to the home operators posi tion, taking up the plug of the trunk circuit 105106 and inserting itinto the multiple of thedesired line. Since the lamp 213 is flashing at a fast rate, both the home and adjacent opera-tors recognize that the call is one which the adjacent operator has, as.-

signed and that the adjacent operator should-attend to its extension. From this point, the call proceeds in exactlythe same manner as though the-home operator had attended to it. 7

Had the call come inupon-ya trunk circuit at, position No. S of the first group and the operator at such position been too busy to attend to it at thetimepand; the adjacent operator at position 1 ot' thegnext group of positions had attended tothe call, then relay 116 would have become operated by ground connected tothe conducto1 13O extending to the rarmature ;contact of the relay corresponding: to relay 123 of such adjacent operators indicator. With relay 116 energized, relays r114 and 115,-associ-ated With 1 the first group of operatorspositions-and relays 117 and 118 associated Witll the-neXt-intermediate group of positions become intermittently operated under the control of the interrupters 10T and 108. Theeircuitior relay ll lunay be traced "from battery through the Winding of this Il-21y, l7l16'lIHIQIIDOStlOWGT' armature and contact of relay'116, conductor 128to ground through i interrupter 107. The circuit for.1'elay--115 -may be traced from groundthrough the inding of this relay, uppernost arn'iatureyand contact of relay 116, conductor -129;to battery throughinterrupter 1 08. Th'ecircuit for-relay 11-7 may be traced from battery through the Winding of relay ,117, conductor 131, the lowermost armature and contact of relay 116, conductor 128 to groun'dthrough interrupter 1(9'4". Thecircuit for relay118 nlay-be traced i 'om:gr0und through the Winding of this relay, conductor 1 82, the innermost upper armature and contacted relay 116,- conductor ,129 to battery through interrupter 108.

Thio-ughthe intermittent operation of re ays 114 and 1-15, ground potential is intermittently applied to'conduotors 134 and 133, respectively, corresponding :to conductors 112 and 113, for -liashingthe lamps of the trunk circuits of theSth position in the first group. Similarly, relays 1'17 and 118 furnishinterrupted ground potential to conductors 135 and 136 corresponding tocon- 1 ductors 112 and 113, for flashing the assignment lamps of all trunlncircuits of the first Y position ct-the intermediate group. It will, cit-course, be understood thatonly one lamp of each position will actually he' l-lashed,

SlIlCB it is possible for theoperatorat a position to assign but one trunk at "a time to her indicator mechanism.

The control of the application of -inter mittent current to the lamp circuits of "posi- ='tions in succeeding groups is exercised in substantially the manner herein'b'efore described and further detailed description thereof is therefore notnecessary. From the foregoing it Will be apparent that the accidental:grounding of any lamp circuit possible load upon either of the interrupters-at given instant is materially reduced. V

F'vVh-at is claimed: is: V

;1. In a; telephone-exchange system, a plurality ofoperators positions divide'dinto groups, trunlrcircuits incoming to saidi positions asignalindividualto each of said trunk circuits, a signal operating means common to:;all of said trunk circuits, "relay means common; to each group of'operators positions for "associating means -With-the signal of any ofsthe trunk circuits incoming to the positions of the re spective groups, and means operative F upon the response ofany operator at a group of position-s for energizing the :rel'ay 'means common; to said group.

2. 111 a telephone exchange system,' a plurality of operators positions divided 'into groups, an indicator rat .each f'of said 1positions, trunk circuits -incomingrto said positions, a signal individual toeach of said trunk circuits, a signal :operatihg :means common toall ofsaid'trunk circuits, relay means common to eachgroup or operators positions i lor "associating means with thesignal otany of the-trunk circuits'incoming to, the positions'o-t the respective groups, and means operative when any indicator ofthe group of positions is assigned "to an incoming trunk foro-perating the relay means common to "saidzgro-up.

3. Ina telephone exchange system, aplurality of operators positions divided into groups, trunk circuits incoming to said positions, a lamp signal individual to each of said trunk circuits, an interrupter common toall of said trunk circuits, relay means common to the operators positions of each group for associating said interrupter with the signal'ol any of the trunk circuits incoming to the positions of the respective groups to flash said signal, andm'eans operativeupon the response of any operator at a group of positions for energizing the relay means cominoiito'the operators positions of said group.

4. In a telephone exchange system, a plurality of operators positions divided into groups, trunk circuits incoming to said p0- sition's, a lampsignal' individ-ualto each of said trunk circuits, an interrupter common .to all of said trunk circuits, and means common 'to ad acent operators positions of ad- JO1II1I1g groups for associating said interrupter with the signal of any of the trunk circuits incoming to the positions of said adjoining groups.

said operating.

5. In a telephone exchange system, a plurality of operators positions divided into groups, trunk circuits incoming to said positions,'a lamp signal individual to each of said trunk circuits, an interrupter common to all of saidtrunk circuits, means common to the operators positions of each group for associating said interrupter with the signal ot'any of the trunk circuits incoming to the positions of the respective group, and means common to adjacent operators positions of adjoining groups for associating said interrupter with the signal'ot any of the trunk circuits incoming to thepositions of said adjoining groups. I

6. In a telephone exchange system, a plurality of operators positions divided into groups, trunk circuits incoming to said positions, a signal individual to each of said trunk circuits, an interrupter common to all of said trunk circuits, a relay common to the operators positions of each group for associating said interrupter with the signal of any of the trunk circuits incoming to the positions of the respective group, and means operative upon the response of any operator at a group of positions for energizing the relay means common to the operators positions of said group. i

7. In a telephone exchange system, a plurality of operators positions divided into groups, trunk circuits incoming to said positions, a signal individual to each of said trunk circuits, an interrupter common to all of said trunk circuits, a relay common to the operators positions of each group for associating said interrupter with the signal of any of the trunk circuits incoming to the positions of the respective group, and .a second relay common to adjacent positions of adjoining groups for associating said interrupter with the signal of any of the trunk circuits incoming to the positions of said adjoining groups. p 8. In a telephone exchange system, aplurality of operators positions divided into groups, trunk circuits incoming to said positions, a signal individual to each of said trunk circuits, an interrupter common to all of said trunk circuits a rela T for a) 31 in 7 O operating potential to the circuits of all signals of thepositions of a group, and a second relay under the control of any operator of the group of positions for connecting said first relay'with said interrupter whereby said first relay is intermittently operated. V

9. In a telephone exchange system, a plurality of operators positions divided into groups, trunk circuits incoming to said po sitions, a lamp signal individual to each of said trunk circuits, an interrupter common to all of said trunk circuits, a relay for applying operating potential to the circuits of all signals of the positionsot' a group, a

second relay under the control of any operator of the group of positions for connecting said first relay with said interrupter, and a third relay under the control of adjacent positions of adjoining groups for associating said interrupter with said first relay whereby, upon the operation of either said second or third relays, said first relay is intermittently operated to flash said signal.

10. In a telephone exchange system, a pinrality of operators positions divided into groups, trunk circuits incoming to said positions, apparatus at each of said positions, means operable to extend a trunk circuit to the apparatus of either of two adjacent positions, a signal for each of said trunk cir. cuits, and means common to the positions of each group and responsive to said last named means for operating said signal distinctively to indicate to which apparatus said trunk circuit is extended.

11. In a telephone exchange system, a plurality of opera-tors positions divided into groups, trunk circuits incoming to said positions, an indicator at eachof said positions, a signal associated with each of said trunk circuits, a key for each trunk circuit for extending it to the indicator of the position to which the trunkis incoming, a second key for each trunk circuit for extending it to the indicator of an adjacent position, signal operating means common to all of said trunk circuits, and means common to the positions of each group and responsive to the operation of either of the keys of each trunk circuit incoming to a group of positions to effect a distinctive operation of said signal for indicating to which of said indicators a trunk circuit is extended.

12. In a telephone exchange system, a plurality of operato-rs positions divided into groups, trunk circuits incoming to said positions, an indicator at each of said positions, a signal associated with each of said trunk circuits, a key for each trunk circuit for extending it to the indicator of the position to which the trunk is incoming, a second key for each trunk circuit for extending it to the "indicator of an adjacent position, means common to all of said signals for intermittently operating them at different rates, means common to eachgroup of positions and responsive to the operation of one of said first mentioned keys of the group for causing the intermittent operation of an associated signal at one rate and responsive to the operation of one of said second men-,

tioned keys of the group for causing the intermittent operation of the associated signal at a different rate.

13. In a telephone exchange system,'a plurality of operators positions divided into groups, trunk circuits incoming to said positions, an indicator at each of sand positions, a lamp signal individual to each trunk circuit, a key for each trunk circuit for extend-, ing it to the indicator of the position to which the trunk circuit is incoming, a second key for each trunk circuit for extending it to the indicator of an adjacent position, a low frequency interrupter and a high frequency interrupter both common to all lamp signals, means common to the operators positions of each group and responsive t0 the operation of a first mentioned key of the respective group for associating said low frequency interrupter with the signal of the corresponding trunk circuit and responsive to the operation of a second men tioned key of the respective group for associating said high frequency interrupter with the signal of the corresponding trunk circuit, and means common to adjacent operators positions of adjoining groups for associating said interrupters with the signals of the trunk circuits incoming to the positions of said adjoining groups.

14. In a telephone exchange system, a plurality of operators positions divided into groups, apparatus individual to each group but common to the positions of a group, means to render the apparatus of a group active under the control of any position in such group, and means torender simultaneously active the apparatus 01"? adjacent groups under the control of a position adjacent an adjoining group.

15. In a telephone exchange system, a plurality of operators positions divided into groups, apparatus individual to each group but common to the positions of a group, means to render the apparatus of a group active under the control of any position in such group, and means to render simultaneously active the apparatus of adjacent groups under the control position of adjoining groups.

In Witness whereof, I hereunto subscribe my name this 6th day of February A. D., 1923.

JACK F. DAHL.

of either adjacent

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