US1739178A - Automatic telephone system - Google Patents

Description

' Dec. 10, 1929. H. R. PARSHALL 1,739,178

AUTOMATIC TELEPHONE SYSTEM Filed Oct. 25. 1926 QU@ @is a K L lq o to KT v NIN 'Harry E Fal-'shall Patented Dec. 10, 1929 UNITED STATES PATENT OFFICE HARRY R. PARSHALL, F CHICAGO, ILLINOIS, ASSIGNOR TO AUTOMATICiELECTRIC INC., OF CHICAGO, ILLINOIS, A CORPORATION OF'DELAWARE Y AUTOMATIC TELEIHONE SYSTEM Application filed October 23, 1926. Serial No. 143,558.

This invention relates to telephone systems in general, but more particularly to small automatic telephone systems.

In'small systems of this type it is customary that all of the special service trunks, for

instance, information, complaint, intercepting, and inspectors trunks, terminate in a single switchboard on account of the fact that there are not sufcient calls of thisnature to warrant separate positions for each type of service. A Single operator or attendant is capable of handling all the calls coming into such a switchboard. The invention relates to equipment used by the operator for handling calls coming in at the switchboard and more particularly to an improved single plug ended cord circuit arranged for extending calls either through the cord circuit from a calling to a called subscriber, or direct from the operator to a called subscriber when the operator is the calling party.v

The various features of the invention will be described in detail in the following specilication in connection with theexplanation of the operation of t-he various circuits which are described with the aid of the accompanying drawings.

Referring now to the drawing, there is shown by means of the usual circuit diagram a trunk circuit TC, an improved single plug ended cord circuit CC, an operators headset O, and a rotary lineswitch LS for extending calls.

rEhe trunk circuit TC and similar trunk circuits extend from the banks of automatic Strowger selector switches in thev regular trunking arrangement and terminate at the switchboard in jacks such as jack J. A trunk circuit of this type may be used for handling complaint or information calls, or may be used as an inspectors trunk.

The cord circuit CC at the operators position terminates in one end in the plug P and at the other end in the conductors 45 and 46 which extend through an intermediate distributing frame to a; rotary lineswitch LS. In the cord circuit CC there is provided a two-way, locking, lever type key TK and DK used for talking when operated in one direction and for dialing when operated in the opposite direction. The key as shown is in normal or neutral position. A'number of relays are also shown in this cord circuit, the circuits of which in combination with the talking and dialing keys permit special operating features to be performed.

rIhe operators headset O shown directly above the cord circuit is provided with a calling device CD and the usual instrumentalities for permitting her to converse with either the calling or called subscriber.

The lineswitch LS is located in the automatic switchroom and is of the well known rotary' type, in which the wipers have no normal position and remain in the position last used. The rotary lineswitch LS has access to selector switches in the regular trunking arrangement of the automatic exchange thereby enabling the operator to extend a connection or complete a connection to any one of the subscribers in the automatic exchange.

Vith this general description of the drawings in mind, the operation of the circuits may now be explained in detail. For this purpose, it will lirst be assumed that an inspector is calling in on the trunk circuit and that it becomes necessary for the operator to extend the call through the regular train of switches to a subscribers line. The calling party dials the proper digits to trunk the call through the automatic switches to an idle trunk circuit, which we will assume is the trunk circuit TC. When the selector yseizes the trunk circuit TC, which it does over Vconductors 1, 2, and 3, relay 5 energizes over the following circuit: from ground through the upper winding of relay 5, armature 13 and its resting contact, conductor 1, through the calling partys loop, conductor 3, resting contact of armature 14 and said armature, and lower winding of relay 5 to battery. Relay 5, upon energizing, closes at armature 10 and its working contact a circuit for lighting the call lamp L; at armature 11 and its working contact connects the ring back tone machine RB to the calling line in the well known manner; and at armature 12 and its working contact closes a circuit for energizing slow acting relay 4. Relay 4, upon energizing, prepares a locking circuit for relay 7 at armature 9 and its Working Contact; and at armaturel 8 and its Working contact connects ground to the release trunk conductor 2, thereby making the trunk circuit TC busy to r other selectors having access thereto and providing a holding circuit for the operated switches. Y

The operator at the switchboard perceiving the lighted condition of the lamp Linserts the plug P ofthe cord circuit-'GC into the u jack J of the trunk circuit TC. Responsive to the insertion of the'plug P into the.

jack J, a. circuit is closed for energizing relays 6 and 7 of the trunk circuit T] and the u relay 2O ot the cord circuit CC in series, as follows: from ground by Ways-ot armature and lits resting contact, restingcontact controlled by spring 38 ofthe dial key ,DK- and said spring, relay 20, sleeve conductor of plug ,A l), sleeve of ack J, spring 19 and-its Working contact, upper winding'of relay 7,- and Winding of relay 6 to battery. Relay 6, upon energizing over the above traced circuit, opens at armatures 13 and 14 thecircuit ,for relay 5; and at armature 15 land its Working 'contact maintains the slow acting-relay 4 en-V ergized. Relay 7 upon energizing, at armature 18 and its resting contact disconnects the ring back tone machine RB; at armature l17 .closes a locking circuit for itself-,and at armature 16 extinguishes lamp L andV prepares a circuit for lamp L. Relay 5, upon deenergizing, at armature 12 opens `the origina-l ergizing circuit of relay 4, which vhowever is now maintained energized from ground at armature 15. It may be mentioned here, that the disconnection ot' the ring back tone ir.- dicates to the calling party that the operator has answered.

In the cord circuit CC relay 20, upon energizing, disconnects resistance 85 and battery from armature 36, and at armature opens a point in the circuit orn relay 21. lt will be noted that the relay 22 is short circuited by the dial key DK at springs 33 and its resting contact. Relay `22'is prevented from operating by this shunt circuit so as not-to initiate the operation of the linesWitCh LS.' With this arrangement the linesvvitchis prevented from operating and ldoes. not therefore tie up a trunk at this time.

After the insertion of plug P into'the jack J, the operator or attendant atthe switchboard will operate the talk key TK and converse with the calling party. By the operation ofthe talk key TK, the operators headset O is connected directly across the .trunln It `Will' be observed lthat the retardation coil 25 furnishes talkingbatteryfor the calling party through i resting vcontacts -on-v armatures 39. and 42.

The operator or attendant, upon ascertaining that it is Ydesirableto connect the calling party with an automatic subscriber in theexchange, restores the talk key .TK and operates the dial key DK. Responsive to the operation of dial key DK, spring 33 and its resting contact are separated thereby rendering effective a circuit for operating relay 22 in series With the sleeve relay 20. At the dial key springs 32 and 34, the cord circuit is divided into two sections and the operators calling device CD is bridged across the talking conductorsrof the outgoing section. Relay-22,jupon energizing, `over the above traced'circuit closes at armature 40 andv its .Working contacta circuit for the electropolarized relay 23 (not operated at this time), a-.circuit-or lighting supervisory lamp L2; andfat armature41 and its Working contactprepares a ,bridge across the' outgoingy trunk which :bridge includes the retardation coil 24 and the upper Winding of the electropolarized relay 28. Relay 22, at armatures 39 vand 42 and their resting contacts disconnects the battery-'feed relay 25 and at its Working ycontacts connects the calling device directly across the :trunk concluetors and 46. Arcircuit may now be ytraced for operating relay 27 of the lineswitch LS as follows: from ground, resting contact of armat-ure 49 and said armature, conductor 46, Working Contact of armature 42 and said armature, Working cont-act of the dial key DK controlled by springs 34 and said spring, the impulse springs of the callingv device CD, spring 32 of .the.calling device key, DK and its Working contact, armature .89 and its Working' contact, conductor 45, armature 47 and its resting contact, and Winding of re` lay 27 to battery. Relay'27 energizes and closes a circuit for t-he switching relay 26 and the stepping magnet 28 in series at armav ture 51, and connects the Wiper 54 to the junctions of the switching relay 26 and stepping magnet 28 at-armature 50.

The operation of the linestvitclrV LS depends upon the busy or idle condition-of the trunk upon which the lineswitch Wipers are resting. In case the trunk upon Which the Wipers of the linesWitch are resting is idle, switching relay 26 energizes immediately. Assuming the relay 26 is short circuited from ground at the test Wiper 54 and does not energize. The Wipers 53, 54, and 55, are rotated step-bystep in a buzzer like manner by the action of the stepping magnet 28, Which operates from ground on the busy test contacts encountered by the testvviper-54.y l/VhenA an idle trunk is reached,-Which will be assumed torbev the trunk.comprising-conductors 56, 57, and 58, thestepping magnet 428 Will stop its stepping operation, and relayv26j, being no longer short circuited,-energizes in series With stepping magnet 28.A Stepping magnet 28 -does not operate at this time on account of tie high resistance of thesvvitching relay 26. Relay 2 6, upon energizing, opens the trunk to be busy, switching' iis 49 'and at armature 48 prepares a holding circuit for itself. At armatures 47 and 49, relay 26 disconnects the line conductors 45 and 46 from the winding of the line relay 27 and ground, and extends them by way of wipers 53 and 55, conductors 56 and 58 to the line relay of the selector in which the selected trunk terminates. The line and release relays of the selector energize in known manner and the release relay connects ground to conductor 57, thereby completing the holding circuit for relay 26 before relay 27 falls back.

The operator may now dial the digits oi the desired number. Responsive to dialing, the selector and other automatic switches necessary to extend the connection to the desired line are operated in the well known manner. During the operation of the calling device CD the shunt spring G2 engages its working contact thereby causing the operation ot relay in the operators circuit. The operation oit relay 60 causes the circuit to the operators headset to be opened at armature 61 and its resting contact. Although this operation is of no utility at this time, it is essential when the operator dials on other trunk circuits (not shown) with which the headset is intended to be used.

llVhen the operator has finished dialling, she restores the dialling key DK.V Since relay 22 is now energized, the normal short circuit around this relay is not again closed, due to the open Contact at armature 40.

`When the dial key is restored the calling device bridge is replaced by the bridge previously mentioned, including relays 23 and 24. The electropolarized relay 23 is not en ergized because the flow of current through said relay is in the wrong direction.

Then the called party answers, respon-A sive to ringing current applied by the connector switch7 which is the last switch in the train operated by the operator, the back bridge relay in the connector switch energizes and reverses the direction ofcurrent flow in conduct-ors 45 and 46 in the regular way. The iiow of current is now in the proper direction to energize relay 23. i

At armature 43, relay 23 opens the circuit of the supervisory lamp L2, thereby notify ing the operator that the called party has ans 'ered. The calling and called parties may now converse with each other desired.

Upon the termination of conversation and responsive to the hanging up of the receiver by the called party the back bridge relay of the connector releases and reverses the current Vflow over conductors 56 and 58 so that the yelectropolarized relay 23 deenergizes. Relay 23, upon deenerg'izing, again closes the circuit forY supervisory'lamp L2 at armature 43 and its resting contact. The operator, upon observing the lighted condition of lamp L2, removes the plug P from the jack J thereby opening the circuit of relays 20 and 22. Relay 22, upon deenergizing, opens the circuit of the supervisory lamp L2, and at its other armatures 39, 41, and 42 opens the bridge from across the trunk conductors 45 and 4G. The removal of the bridge across the trunk conductors 45 and 4G results in the release of the line switch LS and the automatic switches used in extending the call. 1When relay 2O deenergizes, the cord circuit CC is available `for extending other calls.

Responsive to the removal oi' the plug l? from the `iack J, the circuit of relays 6 and 7 opened. Relay 6 deenergizes but relay 7- is maintained energized over armature 17 and its working contact. Assuming that the calling party has hung up his receiver, relay 4 deenergizes after an interval responsive to the opening of its circuit at armature 15. TWhen relay 4 deenergizes, said relay opens at armature 9 and its working contact the locking` circuit ot' relay 7 whereupon relay 7 deenergizes.

ssuming, however, that the calling party for somereason does not replace his receiver and wishes to again talk with the operator, under such conditions relay 5 energizes over the calling partys loop as soon as relay 6 deenergizes. Relay 5, upon reenergizing, closes at armature 12 and its working contact the circuit for maintaining slow acting relay 4 energized; and at armature 10 and its working contactcloses a circuit for lighting the hold lamp L as follows: from ground working contact of armature 10 and said armature, armature 16 and its working contact to lamp L and battery. At armature 8 and its workinS1 contact relay 4 maintains ground on release conductor 2 thereby holding the switches operated by the calling party. rllhe operator again inserts the plug P into the jack J and converses with the calling party and extends the call in the same manner as previously described if the same is desired.

When the calling party hangs up after the removal orn the plug P slow acting relay 4 -deenergizes after an interval and removes ground from the release trunk conductors 2 thereby allowing the switches operated by the calling party to release in the well known manner.

In small telephone systems, as suggested in the lirst paragraphs of this specification, the operator may be required to perform special duties and accordingly it may so happen that the operator desires to be connected with a subscriber in the automatic exchange. The cord circuit CC is arranged so that it is unnecessary or the operator to plug in on an idle ack in order to complete a connection to a called subscriber. Assuming that the operator at the switchboard wishes to converse with some subscriber in the exchange, the operator will operate her dial key DK and dial the digits necessary to complete the con nection to the called subscriber. 1iiiesponsive to the operation of the dial key DK a circuit is closed for relays 21 and 22 as follows: from ground through winding of relay 22, spring 33 of the dial key DK and its working contact, working contact of armature 37 and said armature, and winding of relay 21 to battery. Relay 21, upon energizing, closes a locking circuit for itself and relay 22 at armature 38 and its working contact through the spring 30 and its resting Contact of the talking key TK. Relay 22, upon energizing, at armature 40and its working contact, closes a circuit for the lower winding of polarized relay 23. Relay 23 will not energize over this circuit on account of it being an electropolarized relay. Relay 22, at armature 40 and its resting contact, opens a point in the shortcircuit around itself so that it will be maintained energized when the dial key DK is restored to normal position. At armature 41 and its working Contact, relay 22 prepares a bridge across the trunk conductors 45 and 46 for holding the automatic switches. At armatures 39 and 42, relay 22 bridges the calling device CD across the trunk conductors 45 and 46 thereby causing the operation of the lineswitch as has been previously eX- plained.

The operator now dials the digits required to extend the call to the desired subscriber. In response to the digits dialled by the operator, the selector s vitch seized by the lineswitch LS and other switches respond to extend the talking connection. The last switch, being a connector switch, operates to complete the connection to the called subscribers ine; signals the called subscribers line; and finally completes the talking connection when lthe called subscriber removes his receiver, as

is well known in the art.

When the operator has completed dialling the desired subscribers number, she restores the dial key DK to normal. In so doing, electro-polarized relay 23 is bridged across the conductors 45 and 46 inseries with the retardation coil24, relay 22 being in operated position. rlhis bridge serves to hold the auton'i'atic switches in the established connection .between the operator and the called subscriber direction of this current flow however is o .i-

posite to that necessary to canse the operation of relay 23; relay 23, therefore, remains inoperative at present. `In response to the removal of the receiver of the called substation, a relayY operation in the connector switch takes place, which reverses the current flow over the trunk conductor 45 and 46 and through the winding of relay 23. This results in the operation of relay 23 which opens the circuit of the lamp L2 at armature 43` The extinguishing of the lamp L2 indicates to the operator that the called subscriber has answered. The operator, upon observing the extinguishing of the lamp L2, throws the talk key TK to tall-:ing position thereby connecting her headsetdirectly across the trunk conductors 45 and 46.

Responsive to the operation of talk key TK the locking circuit of relays 21 and 22 is opened at spring 30 and its resting contact. Relay 21 deenergizes but relay 22, however, is maintained energized over the following circuit: from ground through winding of relay i 227 spring 30 of talk key TK and its working Contact, armature 36 and its resting contact, resistance 35 to battery.

The operator and the called subscriber may now converse. l/V hen conversation is nished the operator restores the talk' key TK to its normal position, whereby' the circuit for relay 22 is opened at springs 30 ofthe talk kej,1 TK. When relay 22 deenergizes, said relay removes the bridge from across the conductors 45 and 46 thereby allowing the switches to release in the manner as previously explained.

Having described the invention, its utility and operation, what is considered new and is desired to have protected by Letters Patent will be set forth in the appended claims.

What is claimed is:

1. ln a telephone system, a cord circuit eX- tending to an automatic switch, a dialling key and a talking key in said 'cord circuit, means responsive to the operation of said dialling key for initiatingthe operation of said switch, means for holding the switch after the dialling key is restored, and means whereby the release of said switch is controlled by the subsequent operation of said talking key to its talking position and then to its normal posit-ion.

2. In a telephone system, a cord circuit terminating at one end in a lineswitch` a dialling key and a talking key in said cord circuit, a relay in said cord circuit having contacts for connectino` saidline switch to the talking conductors or said cord circuit, means responsive to the operation of said dial key for energizing said relay to close said contacts to initiate the operation of said lineswitch, means for maintaining said relay energized after said dial key is restored to normal, means for maintaining said relay energized after the talkingl key has been operated to talking position; and means responsive to the restoration of the talking key to normal position for deenergizing said relay whereby said line switch is restored to normal position.

3.` In a telephone system, a cord circuit for use in connecting a calling party and a called party, a relay and a key individual to said cord circuit, a shunt circuit around said relay, contacts controlled by said key when actuated for opening said shunt circuit, a circuit for energizingv said relay when the shunt circuit is opened, and means for maintaining said relay energized during conversation between the calling and called parties.

l. In a telephone system, a single plug ended cord circuit terminating in one end in a plug and in the other end in outgoing trunk conductors, said conductors normally disconnected from the talking conductors of said cord circuit, a relay and a key individual to said cord circuit, a shunt circuit around said relai, contacts controlled by said key when actuated for opening said. shunt Icircuit, circuit for energizing said relay when the shunt circuit is opened, a calling device bridged across said trunk conductors responsive to the actuation of said key and relay, contacts in said shunt circuit opened by said relay whereby said relay is maintained energizedafter the key is restored, and a second bridge closed across said'trunk conductors'through contacts of said relay when the key is restored.

. 5. In a telephone system, a cord circuit at an operators position, a dialling key, a talking key, a first relay, and a second relay in said cord circuit, means for energizing said relays responsive to the operation of said dialling key, means for maintaining said relays energized after the restoration of said dialling key, means for deenergizing said second relay and for maintaining said first relay energized responsive to the operation of said talking key, and means for deenergizing said first relay responsive to the restoration of said talking key.

6. In a telephone system, a cord circuit at an operators position, a dialling key, a talking key, a first relay, and a second relay in said cord circuit, means for energizing said relays responsive to the operation of said dialling key, means for maintaining said relays energized afterV the restoration of said dialling key, means for deenergizing said second relay and for maintaining said first relay energized responsive to the operation of said talking key, means for deenergizing said first relay responsive to the restoration of said talking key, trunk circuits terminating at said operators position, and means for rendering only said first relay responsive to the operation of said dialling key and for rendering the control of said first relay by said talking key ineffective whenever said cord circuit is connected with any one of said trunk circuits.

7. In a telephone system, a cord circuit at an operators position, a dialling key, a talking key, a first relay, and a second relay in said cord circuit, means including a local circuit in said cord circuit for energizing said first and second relays in series responsive to the operation of said dialling key, contacts on said second relay for closing a second local circuit to maintain said relays energized after the restoration of said dialling key, means for opening said second local circuit to deenergize said second relay and for maintaining said first relay energized over a third local circuit responsive to the operation of said talking key, and means for opening said third local circuit to deenergize said first relay responsii'etothe restoration of said talking key.

8. Ina telephone system, a cord circuit at an operators position, a dialling key, a talking key, a first relay, and a second relay in said cord circuit, means including a local circuit in ksaid cord circuit for energizing said first and second relays in series responsive to the operation of said dialling key, contacts on said second relay for closing a second local circuit to maintain said relays energized after the restoration of said dialling key, means for opening said second local circuit to deenergize said second relay and for maintaining said first relay energized over a third local circuit responsive to the operation of said talking key, means for opening said third local circuit to deenergize said first relay responsive to the restoration of said talking key, trunk circuits terminating at said operators position, and means for opening said local circuits Vto render the same ineffective whenever said cord circuit is connected with any one Vof said trunk circuits.

9. In a telephone system, a trunk line terminating at one end in a plug ending cord circuit at an operator-s position and terminating at the other endin an automaticswitch, relay in said trunk line, means for operating said relay only in case the operator initiates a call without inserting said plug in any ack at said position, and means for thereafter automatically operating said switch to use said trunk line as an outgoing trunk line.

l0. In a telephone system, a trunk line terminating at one end in a plug ending cord circuit at an operators position and terminating at the other end in an automatic switch, other trunk lines terminating at said position in jacks, said cord circuit used for answering calls extended over said other trunk lines and for extending such calls by way of said switch, a relay in said cord circuit, means for operating said relay only in case the operator at said position initiates a call herself without inserting said plug in any jack at said position, and means for thereafter automaticallyoperating said switch to extend the connection responsive to the initiation of the operators call.

1l. In a telephone system, a trunk line terminating at one end in a plug ending cord circuit at an operators position and terminating at the other end in an automatic switch, an operators impulse sender at said position, a dial key in said cord circuit, a circuit controlled by said key for connecting said sender to said cord circuit while the sender remains in normalposit-ion, and means for operating said switch to extend a connection responsive to the operation of said dial key mam Whenever the operator, initiates av call herself Without inserting said plug of the cord'circuit in 'any jack at said position and Without operatingsaid sender.

5 l2.- In a telephone system, a cord circuit terminating at one end in a plug and terminatingat the other end in an automatic switch, means including the plug of said cord Circuit for answering calls, means including an vop- 10 erators impulse sender and said switch for extending such calls, and means including said sender for operating said switch to eX'- tend ya connection Without completing any connection to the plug of said oord circuit and .1 5 Without operating said sender.

13. Inv a telephone system, a cord circuit terminating in one end in an automatic switch, altallring key in said oord circuit, means for initiating the operation of said 2G switch, means for holding the switch in operated position, and means whereby the release of'said switch is controlled by the subsequent opera-tion Vof said talking key to its talking position and then to its' normal posit-ion.

' lIn Witness whereof! I hereunto subscribe my naine this 21st day of October, A. D.,

HARRY R.. PARSHALL.

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