US1113274A - Telephone trunking system. - Google Patents

Description

C. S. WINSTON.

TELEPHONE TRUNKING SYSTEM.

APPLICATION FILED DEC. 10, 1910.

Patented 001. 13, 1914.

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' CHARLES S. WINSTON, OF CHICAGO, ILLINOIS, ASSIGNOB TO KELLOGG SWITCHBOARD AND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

TELEPHONE TRUNKING SYSTEM.

Patented 0a. 13, 1914.

Applicationfiled December 10, 1910. Seriai N 0. 596,650.

. To all whom it may concern Trunking Systems, of which the-following is a SPGCIfiCatIOH.

.My invention relates to trunking cord c rcuits for telephone systems, and more particu'larly to such systems in which supervisory relays are controlled over the line conductors of connected'sub-stations. In certain trunk systems in which supervisory relays are adapted-to be energized upon response of the'called subscriber, and are connected directly to the line conductors of a called telephone line, there is a tendency for such relays to momentarily attract or kick up their armatures when a sub-station is called, dueto a discharge from the line conductors -andbridgedcondensers, through such relays after each application of'ringing current to theline. Especially in trunk circuits, where a relay is locked up responsive to ene-rgization of such supervisory relays, this kickor momentary attraction, causes a premature ..-spec ification and in the appended claims.

Referring to the accompanying drawing, the system there illustrated includes two substations, C and D', which terminate in line -circuits at difi'erent exchanges. The

. cord, circuit A which is in the same 'eX- changezwith the line circuit of sub-station ,ClQ-isawell known four-relay cord cir-v cuit-adapted for connecting to the lines ter' minating in its exchange. The trunk circuit oi which the outgoing end is located in'thesame exchange; with the line of substation is connected to the spring jack 14 inthe exchange of sub-station C by means of the heavily'marked conductors 15 The sub-station 5 is connected to its exchange by means of line conductors 1 and 2 which terminate at contacts of cutoff relay CO. The line relay LR is associated with ,the line of sub-station C- and is adapted upon energization to display the line lamp 3. The multiple. jacks 4, iii-practice, would appear indifferent positions of the switchboard and are adapted to be connected to by the answering plug 5 of cord circuit A. The said cord circuit A also includes a calling plug 6 which is adapted-for connection to spring jacks of other telephone lines in the same exchange, or spring jacks leading to trunk circuits as B in distant exchanges. The'said cord circuit N -also includesha tip, answering supervisory relay 7, and a sleeve answering supervisory relay 8,

which through theircoiiperation control the answering supervisory lamp .9. The calling supervisory relays 10 and 11, are adapted by their cooperation to control the calling supervisory lamp 12. The test relay '13 is connected through normal contacts of relay 11 to the tip contact of the calling plug 6. The operators telephone 0 is adapted for use with cord circuit A and other such circuits which may be used by the same operator: The order wire switch contacts OW are adapted to connect the operators telephone 0 with the operators telephone, 0 in a distant exchange.

3 Spring jack 14 is connected to trunk circuit B at a distant exchange by means of the heavily marked conductors 1-5 and 16 which terminate at the incoming end of the said trunkcircuit B in the windings 17 and 18 of repeating coil 19, the said windings having condenser 20 interposed between their terminais. The other windings 21 and 22 of the said repeating coil 19, have the condenser 23 interposed between the inner terminals, the said windings being connected by means of the heavily marked conductors to the plug 24. The; said trunk circuit B also includes a sleeve supervisory relay SR --and a tip supervisory relayTR, a supervi= sory signal lamp 25 and a ringing lamp 26. Normally in bridge of-the incoming end of trunk circuit B is the high resistance, slow acting relay 27.

The-relay 28. which is of comparatively low resistance to relay 27 is adapted upon operation of tip relay TR, to be connected in bridge of the incoming end of trunk circuit B in place of the high resistance relay 27.

The signal controlling relay SC is adapted, upon response of i called subscriber, to efface-ringing lamp 26 and is locked in its energized position to revent a further display of said lamp until t e plug 24 has been withdrawn from a connected spring jack. The

ringing key of the. trunk circuit B includes four sets of springs 29, each one being adapted to connect a diiierent frequency of ringing current to the terminals of a called party line, for the purpose of ringing selectively any one of the sub-stations connected thereto. The plungers which operate the springs29, are soarranged that the contact springs 30 and the selected springs 29, are closed only when any of the ringing plungers are in a fully depressed position, the said springs30 being common to the actuating plungers for the four contact sets 29. The ringing relay31 is adapted to be energized when the contact springs 30 are closed, so as to connect ringing current to the terminals of the called line and open the talking conductors of the trunk circuit.

The telephone line of sub-station D isequipped similar to that ofsub-station C except that it has four telephones, one being connectedto each of the terminals D, D and D Having described in general the apparatus used in the system illustrated, the op-' eration of the said system in connecting two subscribers in different exchanges will now be described. Assuming subscriber at substation C. desires connection with a subscriber at sub-station D he would remove receiver 32 from its switch hook, thereby establishing a circuit through line relay LR from ground, normal contact 33, line conductors and sub-station C normal contact 34, the winding of relay LR to battery, energizing said relay LR and lighting line lamp 3. The operatorin response to said signal inserts: answering plug 5 into a jack '4, thereby establishing'an energizing circuit for relays 8 and CO traced from battery through the winding of relay 8, the sleeve contacts of plug 5 and jack 4, and through the Winding of relay CO to ground. The said relays are thereupon energized, the cutoff relay CO interrupting the circuit through line relay LR, thereby eiiacing line lamp 3. A circuit for relay 7 is also established from battery over the previously described path to alternate contact 34 of'relay CO, then over the line conductors and through sub-station C, tip contact of jack 4 and plug 5 and through the winding of re lay 7 to ground, energizing the said relay. The operator then actuates listening key 35 toascertain the wants of the calling subscriber.

Assuming, as previously stated, that the calling subscriber at sub-station O desires connection with sub-station D which is in a distant exchange, the operator presses the order wire button OW leading to the exchange in which the line of sub-station D terminatesand inquires of the distant operator which trunk is to be used for the connection. The operator at the first exchange new inserts the calling plug 6 into a jack 14 of the assigned trunk circuit. Responsive .to the said connection a circuit for relay 11 is' established from battery through the winding of said relay 11, tip contact of plug 6 and jack 14, through impedance coil 37 to ground, energizing the said relay 11 and lighting the supervisory lamp 12 over a cir cuit established from ground, through the normal contact of relay 10, alternate contact 38 of relay -11 and lamp 12 to battery. Responsive to the energizatlon of relayll the alternate contact 39 is closed, thereby establishing a circuit through relay 27 of trunk circuit B traced from ground through relay 10, over conductor 16 through winding of relay 27 and back through conductor 15 and relay l1 to-battery, energizing relay 27. The said relay 27 being of a comparatively high resistance, sufficient current does not flow through its winding to the jack ofcalled substation as yet, upon energization of relay 27, lamp 25 Will'light, indicating to the trunk operator that the first operator has connected with the proper trunk, or if the trunk operator 'plugs into a jack 4!), and lamp 25 lights, the trunk operator will know the first operator has not plugged into jack 14, due to relay 27 failing toenergize.

The operator at trunk-circuit B having ascertained from the operator atcord circuit A the number of the called subscriber, now tests the jack 40 of the called subscriberby touching the tip of the plug 24 to the sleeve of jack 40. If the called line is busy, the test relay 41 is energized in a well known manner by battery flowing from the sleeve contact of jack 40, and the operator receives a click in her receiver due to the closing of a circuit through the middle winding of induction coil 42. If the line of the called subscriber is idle there will be no potential above ground on the sleeve contact of jack 40 and test relay 41 Will therefore not energize, and the operator not receiving a busy click inserts the plug 24 into a jack'4O of the called line. Responsive to the said connection an energizingcircuit is established through cutoff relay-CO and the supervisory relay SR, traced from ground through the winding of said relay CO, sleeve contacts of jack 40 and plug 24, conductor 43, through the winding of relay SE to battery.'l" The energization'of the relay CO removes the sub-station control of a line relay LR and also establishes a con. tinuity of the talking conductors of the' trunk circuit B to. the terminals of said sub-station D. Responsive to the energization of relay SE, a circuit through ringmg lamp 26 is established from ground through alternate contact 44, normal contact 45, through said lamp 26 to battery,

lighting the said lamp. The trunk operator now actuates a ringing button to connect the proper ringing generator to the line of the called substation. The actuation of said key closes the proper ringing springs 29 and the cont-act springs 30; and'responsive to the closing of contact springs 30, a circuit through relay '31 is established, from ground through alternate contact 44, normal contact 45, contact 30 to winding of relay 31 to battery at alternate contact 47, energizing said relay 31 and closing alternate contacts 48 and 49. A path for. ringing current 1s thereby established, from generator through the closed alternate contact 29, alternate contact 49, tip contacts of plug 24 and jack 40,- alternate, contact 33 over the line conductors 1', 2, and through the condenser and call bell of sub-station D, alternate contact 34, sleeve contacts of jack 40 and plug 24, through alternate contacts 48 and resistance 50 to ground. The operator actuates the selected key several times to ring the bell of the substation D- and upon each restoration of the actuated key the contact 30 and contact- 29 are restored to normal.

Upon each actuation of the said ringing key, the line conductors and condensers in bridge thereof are charged from the. applied ringing current, and upon each restoration of the said ringing. key, contacts 30 land 29 are opened and the said line conductor and condensers will discharge to ground through the winding of the tip relay TR'causing a tendency-of the said relay TR to kick up its armature, opening the circuit through the slow relay 27 and establishing a circuit through the relay 28 through alternate contact 52. This momentary attrac-' tion of the armature of relay TB is not of suflic'ient duration to allow the relay 27 to.

release its armature, it being slow acting, so that even should relay 28 be energized by current from cord circuit A, the relay 27 not having released its armature, a premature energizing circuit forrelay SC is not closed. It will thus be seen, that-due to the .circuit arrangement just described the relay SC will not be energized to prematurely efi acc the ringing lamp 26.

The trunk operatorhavin signaled the subscriber at sub-station D as described,

upon response of the said subscriber by the removal of receiver 32 from it's switch hook, a circuit for the tip relay TR is established, from ground through the winding of said relay TR, alternate contact 53 of relay SR, normal contact 49, tip contacts of plug 24 and jack 40, over the line conductors and through the called substation, back through sleeve contacts of the jack 4O "and-plug 24, conductor 43,'and the windingsof relay SR to battery. Relay TB is thereupon energized, interrupting the circuit throughrelay 27, allowing said relay to deenergize, and establishing a circuit through the lower re- "sistance relay 28, by the closing of alternate contact 52 of relay TR. The closing of this low resistance path through the winding of relay 28, allows relay 10 of the cord circuit A to energize, elfacing ,the supervisory lamp l2 and notifyingthe operator of cord circuit A that the called subscriber ha responded.

Returning noW to relay 28, upon its said 'energization, a" circuit through the relay SC is established, from battery through normal contact 47 of relay 27, alternate contact 55, through the Winding'of relay SC to ound at alternatecontact44 of relay SR. Responsive to the energization of relay SC the circuit through ringing lamp 26 is' interrupted at contact 45, and the said lamp is in a conversational circuit traced over the heavily marked conductors, talking current for the calling subscriber being supplied through the relays 7 and 8 of cord circuit A, and talking current for the called subscriber being supplied through the relays TR and SR ofthe'trunk circuit B. While I have shown several batteries at each exchange, it is to be understood that they may be one and the same, that is, each exchange to have but a single battery.

Afterthe subscribers have finished conversation they replace their receivers upon their respective switch hooks. The restoratlon of the calling subscribers receiver, opens the circuit through relay 7 of the cord circuit A allowing the said relay to de energize and close a circuit through supervisory lamp 9.

Uponthe called subscriber replacing his receiver upon itssWitch-hook, the previously traced circuit throughrelays TR and SR is interrupted, allowing the said relay TR to deenergize, but the relay SR remains energized dueto thecircuit through the cutoff relay CO. Upon deenergization of tip rclay TR, the circuit through the low resistance relay 28 is interrupted at contact 52, and a circuit through the high resistance re- .lay 27;is againestablished over the pre- A in response to the signal received fromthe lighted lamps 9 and 12, withdraws the plugs 5 and 6 from their respective spring jacks, restoring the apparatusof cord circuit A to. normal and also restoring cutofi' relay C0 of the calling line. Upon Withing the low resistance path through relay 28.

drawal of plug 6 of cord circuit A from spring jack 14.,the circuit through relay 27 of trunk circuit B is interrupted and the said relay is deenerg'ized, and a circuit through disconnect signal lamp 25 is established from battery, through normal contact 4:7 of relay 27, normal contact 55, alternate contact 59, through the lamp 25 to'ground, lighting the. said lamp. The-trunk operator in response to this signal withdraws plug 24 from jack 40-, thus opening the circuit through supervisory relay SR and the cutoff relay CO, allowing the said relays to deen'ergize. Upon deenergization of relay SB thecircuit through signal lamp 25 is interrupted efiacing the said lamp. Also, upon'de'nergization of relay .SR, the locking circuit forrelay SC is interrupted at contact M allowinglsaid relay SC to deen- .ergize and retract its armature. The apparatus of trunk circuit B having now been restored, and being in an idle condition is available for further use.

Should a called subscriber, after having responded to a call, desire to converse With one of the operators, by operating his switch hook, the-circuit through the supervisory relay TR will he -opened, allowing the said relay to retract its armature, thereby openand substituting therefor a high resistance path through relay27, thereby again deenergizing the supervisory relay 10 of cord circuit A and flashing the supervisory lamp 12. ;flhe operator at cord circuit A observing this signal, may connect the operators telephone 0 with cord circuit A and converse with the culled subscriber at substation D. v I

It will be noted that due to the circuit arrangement as heretofore described, that any premature, incidental, momentary energization of the supervisory relay TR will not affect the signal controlling relay SC, and therefor it will require an ener 'zation of relay TB of some duration to e ect an energization of the signal controllingrelaySC.

What I claim as new and desire to secure by Letters Patent is; 7

1. Ina telephone system, a trunk circuit for connectin calling and called substations, compris1ng a trunk supervisory relay adapted to be operativelyenergized uponrespouse from a called substation when connected thereto, a signal controlling relay for said trunk circuit adapted to be energized responsive to a responsive energization of the supervisory relay,- a signal operated responsive to such energization of the signal relay, and means to prevent said signal relay i from being energized responsive to an moidental momentary operation of said supervisory relay.

. 2. In a telephone system, the combination with a trunk circuit of a cord circuit connected to the incoming end thereof, a called subscribers.sub-station connected to the outgoing end thereof, a trunk supervisory relay connected to a talking strand of the called sub-station, adapted to be operatively energized upon response of the called subscriber,

- a signal controlling relay for said trunk circuit adapted to be energizedresponsive to a responsive energi'zation of said supervisory relay, atrunk signal controlled'by said signal relay, means for connecting calling current to said strand, and means to prevent any energization of said signal relay responsive to an incidental momentary operationof said supervisory relay. I

3. A telephone system including a trunk circuit, a link circuit connected to theincoming end thereof, a called subscribers line connected to the outgoing end thereof, a relay in bridge of said incoming end, energized by current from said link circuit, a supervisory relay for said trunk adapted to be energized upon response of the called subscriber, and having normally closed contacts controlling said bridged relay, a signal cont-rolling relay, adapted to be energized responsive to energiza t'ion of said supervisory relay and deenergization ofsaid bridged relay, and means for momentarily holding the armature of said bridged relay attracted and said contacts open, after an energization of said supervisory relay.

4. In a telephone system, a trunk circuit, a relay in bridge of the incoming end thereof, an energizing circuit for said relay, 9.

supervisory relay for said trunk adapted to' be energized uponresponse of a connected called subscriber, a second relay, switch contacts on said supervisory relay adapted upon energization of said supervisory relay to interrupt the energizing circuit of the said bridged relay and include said second relay in said energizing circuit, means for momentarily holding the armature of said bridged relay attracted after its energizing circuit is opened, a signal controlling relay, and an energizing circuit therefor adapted to-be slow relay to deenergize it and substituting said second. relay to be energized, a supervisory relay, adapted to be energized upon response of a called subscriber when connected to, for controlling said switch contacts, a signal controlling relay, and an en ergizing circuit therefor, adapted to be closed upon denergization of said slow relay and energization or said second relay.

6. A telephone system comprising an operator controlled link circuit, a called telephone line and substation connected thereto, a response supervisory relay individual to said link circuit, a signal control relay for said link circuit adapted to be operatively energized by a responsive operation ofthe supervisory relay, a locking circuit for said signal control relay effective upon its energization, a supervisory signal for said link circuit operated when said signal control rewhereby a premature momentary operation of said response relay does not effect any energization of the signal control relay.

7. A telephone system comprising a-link circuit, a slow relay energized by current over the answering end of said circuit, a supervisory relay connected to the calling end of said link circuit and adapted to'be energized upon response from a connected called substation, a third relay, said supervisory relay being adapted when energized to disconnect said slow relay and substitute said third relay to be energized, a signal control relay, and an energizing circuit therefor adapted to be closed when said slow relay is denergized and said third relay energized.

Signed by me at Chicago, county of Cook, and State of Illinois, in the presence of two witnesses.

CHARLES S. WINSTON. Witnesses:

GEORGE E. MUELLER, WM. BERGIELAHN.

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