US2083404A - Telephone system - Google Patents

Description

June 8, 1937. e. N. SAUL TELEPHONE SYSTEM 4 Sheets-Sheet 1 Filed Feb. 28. 1955' m Um lNl ENTOR 6.7V. SAUL A TTORNEY June 8, 1937. G. N. SAUL 2,033,404

' TELEPHONE sYs TEM I I Filed Feb 28, 1935 4 Sheets-Sheet 2 u E Q lNl ENTOR 6. N. SAUL ATTORNEY June 8,1937. G. N. SAUL 2,083,404

I TELEPHONE SYSTEM I A INVENTOR a. /v. SAUL A 7'TORNEV Ju ne 8, 1937.

G. N. SAUL TELEPHONE SYSTEM Iiiled Feb. 28, 1935 4 Sheets-Sheet 4 I l INVENTOR' G. N. SAUL ATTORVEY Patented June 8, 1937 UNITED STATES PATENT OFFICE TELEPHONE SYSTEM George N. Saul, Brooklynp-N. Y,, assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application February 28, 1935, Serial No. 8,591

6 Claims. (011179-43) This invention relates to telephone systems and more particularly to toll switchboardcircuit ar rangements. One object of the invention is to prevent annoying clicks in an operators receiver 5 when she ceases ringing on a called line in case the talk key is operated at the time.

Another object is to prevent ringing current incoming over the calling line from entering the answering operators receiver in case she should insert the answering plug of a cord circuit in the calling line jack while the talking key of that particular cord circuit is operated.

In certain types of switchboard circuits, the operators telephone set is connected to the cord 15 circuit through what is termed a hybrid repeating coil. Such a hybrid coil arrangement is shown in Fig. 4 of the U. S. patent to Dietze 1,709,900.

In the arrangement embodying the present inin vention the networks or impedance N1 and N2 of Fig. 4 of the above noted Dietze patent are normally connected across the respective ends of the coil and are removed only when the respective ends of the cord circuit are connected to line D3 jacks and the talk key is operated.

With this arrangement it will be evident that when the talk key is normal the'repeating coil, with respect to the connected transmitter, is balanced and is what is known as in an anti-sidetone condition, 1. e. a condition such that sounds affecting the transmitter will cause no corresponding efiect in the receiver. At such times it is frequently necessary that a supervising operator, who may have her telephone connected in multiple with the switchboard operator, be

" able to converse with that operator, which under the condition above described would be impossible.

Another object of the invention therefore is to enable a supervisor to talk with the operator at such times, in systems'arranged as above described.

A feature of theinvention whereby the first object is attained resides in disconnecting the operators induction coil from the conductor of 45 the cord over which ringing current is being transmitted, when the, ringing key is operated,

and delay the reconnection of the cord in that direction for an interval sufficient to allow any remaining charge in the line to dissipate.

50 Another feature whereby the second object is attained resides in a switching arrangement whereby in case the cord circuit talk key. is operated at the time the answering'plug of the cord circuit is inserted in the jack of the line over 55 which ringing current is incoming the connection of the operators induction coil to the cord circuit will be delayed until theincoming -ring. ing current ceases.

Still another feature whereby the last object is attained resides in a switching arrangement whereby when the supervisor connects her tele-' phone set in parallel with the set of the regular operator'i'n case no talk key at the position is operated, a circuit will be established to disconnect one of the bridged networks from across the operators induction coil, thereby unbalancing the coil and permitting conversation between the two telephone sets.

The invention will be understood from the followingdescription of a toll switchboard in accordance therewith and illustrated by the accompanying drawings Figs. 1 to 4, arranged in accordance with Fig. 5. Fig. 1 shows a portion of an incoming toll line essential to an understanding of the invention; Fig. 2 shows a toll cordcircuit TC of the so-called sleeve or third wire control type; Fig. 3 is a so-called position circuit. The cord circuit of Fig. 2 and all other cord circuits of the position are arranged to be connected with Fig. 3. Fig. 4 is an operators telephone circuit cooperating with the aforesaid cord and position circuits.

Figs. 1, 2 and 3' correspond to and are identical with similarly numbered figures forming apart of the-disclosure of a copending application filed in the names of Messrs. G. N. Saul and J. B. Shiel,-Serial No. 759,672, filed Dec. 29, 1934, and Fig. 4 corresponds to and is identical with Fig. 5 of the same copending application.

The eleven conductors extending to the left and the five conductors extending to the right of Fig.

4 are not essential to an understanding of the present invention and may be disregarded in the consideration of this application, they being shown for convenience only as they are necessary for an understanding of the before mentioned Saul-Shiel application.

' A description of the operation of the switchboard circuits embodying the present invention will now be given. It will be understood that a distant operator has initiated a call on the toll line TL'of Fig. 1, which call has been brought to the attention of the toll operator having control of the cord circuit of Fig. 2 by the lighting of the usual line lamp, not shown. The operator 0 now inserts the rear or answering plug I of the cord'circuit (Fig. 2) into jack 2 of the calling line. The supervisory lamp 3, however, does not light at this time due to the high resistance to ground through sleeve relay 4 of the calling line.

The operator now actuates. talking key 5,'thereby closing a circuit to operate relay 6 which can be traced from ground at the right-hand outer back contacts of relay 1, over conductor 8, through right-hand upper operated contacts of key 5, and left-hand winding of relay 6 to battery. Relay 6 in operating effects the transfer of certain functional conductors from cord circuit TC to the common position circuit, Fig. 3, by which circuit they are controlled. The control of the before mentioned conductors will be described hereinafter in detail. D V

When relay 6 operated it closed a circuitfor operating relay 1 of Fig. 3f;which maybe traced from battery through thewinding of relay 1,-

over conductor 9, through left and right-hand inner operated make contactS.;,Qf "relay 6 to ground on the lower contacts of key 5. Relay 1 in operating removes ground on its right-hand outer back contacts from conductor 8, thereby preventing the: operation, in another cord cir-- cuit of the position, of another relay corresponding to relay 6, if a talk key 5 of;-another cord circuit should be operated While key 5 of the tacts from sleeve conductor Hi and connects said conductor 10 to conductor II at its contacts 2, thereby completing, a circuit from battery (Fig, 3) through the windings of relays l4 and l5 over conductor H to sleeve conductors l0, and thence through sleeve contacts of plu'g and jack2' and winding of relay 4 tocground. Relay |4 operates in this circuit, but relay |5 which isfmar'ginal' does not operate, at this time. Relay 14in operating: operates relay l8 through a circuit traceable from battery through the winding of relay l8, right-hand break contacts of splitting key IB and relay 20, break contacts of relay l1. to ground on the operated contacts of relay |4. Relay l4 inoperating also closes a circuit from ground through the win'dingof relay=25, over conductor 2|, through operated contacts |3 of relay 6 to lamp 3 and battery; Lamp 3, however, doesnot light due to the high resistance of relay 25. Relay |8- in operating operates relay. 26

through an .obvious circuit, and connects rear tip and ring conductors, 21 and 28, 'with'its operated-.front-contacts to conductors 29inand 30- leading to the operators telephone circuit of Fig; 4.- Rel'ay 26 in operating fdisconnects conductors 29 and 36 from a balancingtermination consisting'of the series. combination of condenser 3|andgres'istance 32, the functioningof which termination being hereinafter described; J

- When relay 6 'operatedit closed a circuitfor I operatingzrelay 22, which may be traced from battery "through the winding of relay; 22, righthand operated inner make contacts of relay 6 to ground on the lower-contacts of talk key 5. Relay 22 in operating-connects with-its upper and lower inner make contactstalkingconductors. 21: and 26120 conductors and 34, which connect through; the normally; closed contacts or ringingkey 35 ,tq cord, circuit conductors- 36 and 31. The toll operator may now converge over the calling line through the tip and ring contacts of plug and jack 2., The aforesaid conductors29 and 30 connect to the right-hand terminals of winding 38 and 39 of induction coil 40. The left-hand terminals of said windings connect over conductors 3| and 42 through lefthand and right-hand inner break contacts of relay 43 to another balancing termination, consisting of a resistance 44 in series with a condenser 45, and balancing the impedance of the toll line connected to the right-hand terminals of windings 38 and 39. The operator's receiver 46 is connected for conversation to induction coil through a circuit traceable from the middle point of winding 38, right-hand break contacts of relay 5|, upper inner break contacts of relay 52', sleeve contacts of jack 4'! and plug 53,

receiver 46, sleeve contacts of plug 54 and jack 48, lower inner break contacts of relay 52, lefthand outer break contacts of, relay 5|, condenser 55 to middle of winding 39. The operators trans mitter 56 is energized through a circuit traced from battery through retardation coil 51, operated local contacts and tip contacts'of jack 48, tip contacts of plug 54,transmitter 56, tip contacts of plug 53 and jack to ground 58. The voice currents generated by transmitter 56 are conducted to winding 59 of induction coil 46 through a circuit in multiple, with the transmitter. This circuit may be followed from conductor 6|], through condenser 6|, lower outer break contacts of relay 52, winding 59 of induction coil 40, upper outer breakcontacts of relay 52 to ground 58. The operators telephone arrangement just described isth'at of thefaforesaid Dietze Patent 1,709,900 and described in said patent.

The operator having received instructions for it functions as completing the call inserts plug 62 of the front cord into jack 63 of the called line. This causes the operation of relay 23through a circuit that may be traced from battery through the windings of relays 23 and 24, over conductor 66, right-hand outer'operated make contacts. of relay 6,.sleeve conductor 61 and sleeve'contacts of plug 62 and l jack 63. Relay 24 is marginal and does not operate at this time. The operation of relay I 23 operates relay 68, through'a circuit traceable from battery through the winding of relay 68,1eft-hand break contacts of splitting key i9, right-hand 5 outer break contacts of relay 69 to ground on the contacts'of relay 23. Relay 68 in operating operates relay 43 through an obvious circuit and connects talking conductors 10 and 1|, to conductors 4| and 42, which connect to theinduction coil 40 I of the operators telephone circuit, as hereinbefore traced. The aforesaid operation ofrelay 43 disconnects the hereinbefore mentioned balancing termination consisting of resistance 44 and condenser45; The operator now actuates front ringing key 64, which connects battery through resistance 65 to the tip conductor of the calling cord through the upper outer make contacts of key 64. This causes-an associated ringing circuit, not shown, to -function in a wellknown manner to connect ring-ing current to the conductors of the called line;

When ringing key 64 was actuated a circuit was closed for operating relay 69 which may be 7 traced from ground through springs of key;64,

lower outer operated contacts of relayf22, over conductor 15, and through right-hand winding of relay 59 to battery. Relay 6!) in operating operates slow releasing relay 16 from ground on conductor 15, through right hand operated inner contacts of relay 69 and winding of relay 15 to battery. Relay 16 in operating closesa circuit through the left-hand winding of relay 69, lefthand inner operated contacts of relay 6E! to ground on the contacts of relay 16.

According to a particular feature of this invention the arrangement described in the preceding paragraph avoids the possibility of the operator receiving disturbing clicks in her re- 10 ceiver from line discharges after the ringing key is restored to normal after ringing. This is accomplished by the slow release characteristics of relay 75, which remains operated for an interval after ground is removed from conductor due 15 to said restoration of ringing key 64. Relay Iii. holds relay 69 through its left-hand winding until it finally releases, thereby preventing the immediate reoperation of relay 6B and the consequent immediate reconnection of conductors l5 and H to the operators telephone circuit of Fig. 4. This delay is sufficient to allow the calling line to dissipate the charge due to the ringing current, and disturbing clicks in the operators receiver are accordingly avoided.

Let it be assumed now that the operator desires to ring on the rear or answering cord. The invention now functions in a manner similar to that described for ringing on the front cord. Ringing key 35 is accordingly actuated and battery through resistance 65 is connected by the upper outer make contacts of key to the tip conductor 35 of toll line TL through the tip contacts of plug I and jack 2. This causes the associated-ringing circuit, not shown, to function. At

35 the same time key 35 also connects ground through its springs TI, lower middle make contacts of relay 22, over conductor '18 through the right-hand winding of relay 20 to battery. Relay 20 operates and opens the operating circuit of 40 relay l8, which releases. Relay 26 also releases and connects the balancing termination consisting of condenser 3| and resistance 32 to conductors 29 and 30, thereby maintaining the balanced condition of the operators telephone circuit.

When relay 2E3 operated it closed a circuit from ground on conductor 18, through its right-hand inner contacts and winding of slow releasing relay 16 to battery. Relay '6 now functions in connection with relay 2!] in the same manner as hereinbefore described in connection with ringing on the front or calling cord, so that the line is discharged before the operators telephone is reconnected following the restoration to normal of the ringing key. Objectionable clicks due to ringing are accordingly avoided.

Let it be assumed now that the distant operator at the end of toll line TL desires to recall the operator having control of cord circuit TC. Ringing current will be transmitted over the line and will operate relay 19, removing ground from its back contacts and causing the release of normally operated relay 80. Relay 80 in releasing operates relay M which connects the winding of low resistance relay 82 in multiple with that of high resistance relay 4. This reduces the resistance of the circuit hereinbefore traced through the windings of relays l4 and i5, and marginal relay l5 now operates and connects ground through resistance 83 to conductor 2|, shunting the winding of relay 25 thereby causing the lighting of lamp 3 over the circuit before traced. If the distant operator on the called line also desires to signal, a similar reduction in the resistance of the sleeve circuit of jack 63 is effected by circuit arrangements not shown causing the operation of relay 24 and the lighting of lamp 84.

Let itbe assumed now that, the conversational connection being established, and all cord circuit keys being normal the operator desires to monitor on the connection. Monitor key 85 will accordingly be actuated and will connect ground through its lower outer make contacts to conductor 86, thence through the left-hand outer break contacts of relay 1 and winding of relay St to battery. Relay 5| operates and transfers with its transfer contacts the circuit of the winding of receiver 46 from induction coil 53 to the left-hand winding of monitoring coil 83. The

right-hand windings of coil 88 are connected in series with condenser 89, through inner break contacts of relay 1, break contacts 33 and 9! of relay 92, over conductors 93 and 9d, and the inner make contacts of monitor key 85 to the talking conductors of the cord circuit. The operator may now listen in on the connection.

If one of the talk keys of a cord circuit are operated, the operator may operate a monitoring key of another cord circuit and monitor on that cord circuit. To describe this condition let it be assumed that the cord circuit whose talk key has been operated has only its front cord plugged up. Under this condition relay 1 is operated, due to the operation of talking key 5, as hereinbefore described. The operation of relay i transfers with its transfer contacts, monitoring leads 93 and 94 (connected to the cord circuit of which the monitoring key is operated) to leads S5 and 36, whichconnect to leads 2% and 30 through condensers 9'! and 33. Leads iit and 3B connect to the right-hand terminals of windings 38 and 39 of induction coil 55. Conductor 86 leading to the winding of monitoring relay 5i is also transferred by the left-hand outer contacts of relay 1 through the left-hand outer break contacts of relay 92 to the winding of relay 26, which operates from ground on said lead 85. The operation of relay 25 disconnects the balancing termination consisting of resistance 32 and condenser 3! from leads 2t and fit. The left-hand terminals of induction coil windings 38 and 39 are connected over leads 4! and 52 and through operated contacts of relay 58 to leads l0. and H, which connect to the talking conductors of the front cord through the operated contacts of relay 22. The toll operator may now converse and listen on both cord circuits simultaneously. If the rear cord of the cord circuit having the operated talk key 5 is plugged up, relay 25 is already operated when ground is connected to its winding by the operation of the monitoring key 85 of the other cord circuit. The operator may monitor simultaneously on both cords as described before.

The invention was described hereinbefore for the conditions existing when the operator actuated the ringing key 35 or 64 on a cord circuit with the talk key 5 of that cord circuit operated. It will now be described for ringing with only a monitoring key 85 operated. Relay 92 is now operated in a circuit from battery through the right-hand winding of relay 92, over condoctor 99, throughupper outer contacts of key 35 to ground on the lower, outside operated contacts of front cord ringing key 54, or rear cord key 35. Relay 92 in operating extends through its right-hand, inner operated contacts the ground on conductor 99 to the winding of slow releasing relay 16, which operates and holds relay 92 through its left-hand inner contacts and winding. Relay 92 in operating opens its break contacts 9 and 9|, thereby disconnecting monitoring leads 93 and 94 duringringing. The actuation of either of the aforesaid ringing keys or 64 causes the associated ringing circuit (not shown) to ring on the toll line, and to connect to the line not being called a balancing termination consisting of resistance 12 and condenser 13. After the restoration of the ringing key, relay 92 is held operated for a moment until relay'lii releases, thereby allowing the charge on the line to be dissipated before the monitoring leads 93 and 94 are reconnected to the cord circuit conductors by the'release of relay 92.

In the preceding paragraph the ringing function was described with a monitoring key operated on one cord circuit, and no keys operated on any other cord circuit. Let it be assumed now that it is required to ring on a cord circuit Whose monitor key is operated, while a talk key 01 another cord circuit is operated. Under this condition relay 1 is operated as hereinbefore described, and the monitoring leads 93 and 94 are accordingly connected to leads 95 and 96. When relay 92 now operates in response to the actuation of the ringing key 35 or 64, the disconnection of leads 93 and 94 is from leads 95 and 96. In other respects the operation is as described in the preceding paragraph.

If it is desired to ringon a cord circuit with no talk or monitoring keys operated, the actuation of ringing 35 or 64 connects the balancing termination consisting of resistance 12 and con denser 13 to the line that is not being called.

To enable the toll operator to talk on either toll line separately, without being heard on'the other line, a splitting key I9 is provided. When the associated key lever is operated to the left, so as to talk on the rear cord exclusively, the operating circuit for relay 68 is opened; Relay 68 in releasing disconnects front cord conductors 10 and H from leads 4| and 42 to the operators telephone circuit, andwhen relay 43 also obviously releases, the front balancing termination is connected to leads 4| and 42.- Inorder to balance the disconnected line-associated with the front cord, the operation of key I9 closes a circuit for connecting the balancing termination consisting of resistance 32 and condenser 3! to the front cord talking conductors l0 and H. This circuit may be traced from conductor 10, through lefthand outer break contacts of relays 68 and 69, left-hand upper make contacts of key l9, condenser 3|, resistance 32, left-hand lower make contacts of key l9, and right-hand break contacts of relay 68, to conductor ll. With this arrangement the operator is enabled to talk on the line associated with the rear cord, without being heard by the line associated with the front cord. In like manner, if splitting key I9 is operated to the right or front position, the operator may converse on the front cord only. In this case relays I8 and 26 release and the termination consisting of resistance 44 and condenser 45 is connected through the contacts of key l9 to the talking conductors 21 and 28 associated with the disconnected rear cord line.

The invention has been described for the usual functions involved in establishing a conversational connection between two toll lines, including ringing, splitting and supervision, and the operation of the operators telephone circuit for talking and monitoring. It will now be described for certain additional features, to which it is desired that special attention be given.

, Let it be assumed now that the toll operator in control of cord circuit TC (Fig. 2) has observed theactuation of the line signal (not shown) associated with toll line TL (Fig. 1) and operatesher talk key 5 before inserting plug I into jack 2. Without the particular features'of this invention, which will now be described, it is to be expected that the operator will frequently hear in her receiver disturbing clicks due to the ringing current still connected to the toll line at the time of plugging in. Due to the operation of talk key 5 relay 1 is operated as before described. Slow release relay H operates through a circuit traceable from battery through the winding of relay l1, break contacts of relay 25 to ground on the right-hand outer operated contacts; of relay 1. Relay I! in operating opens withits break contacts the operating circuit for relay I 8. When plug l is inserted into jack 2, if ringing'relay I9 is operated the sleeve resistance of jack 2 will be low and both relays I4 and l5'will operate. Under this condition relay 25 cannot operate due to the shunting effect of resistance 83- connected to ground to the contacts of relay l5. Relay ll accordingly remains operated and keeps open the operating circuit of relay I8, which in not operating does not connect talking conductors 2'! and 28 to the operators telephone circuit. Accordingly ringing current is kept out of the operators receiver. When, however, ringing current ceases, relay l5 releases, removing shunt 83 and relay 25 operates, through a circuit from battery through lamp 3, operated contacts l3 of relay 6, over conductor 2|, through winding of relay 25 to ground on the operated contacts of relay I 4. Relay '25 I in operating releases relay [1, which closesthe circuit of relay l8 which operates, and connects leads 2'! and 28 to'the operators telephone circuit, thereby enabling the operator to converse on th calling line.

Another feature of the invention will now be described wherebyan arrangement is provided to enable a supervisor to communicate with the toll operator by plugging in her telephone set in multiple with that of the operator when the cord circuit talk keys-are normal. As hereinbefore described, the operators telephone circuit, when. no talk key is' operated, is balanced by the connection of a termination consisting of resistance 44' and condenser 45- to the left-hand terminals of windings 38 and 39 of induction coil 40, and of a termination consisting of resistance 32 and condenser 3| to the corresponding right-hand terminals of said winding. Under this balanced condition a telephone set in multiple with that;

of the toll. operator would be ineffectivedu'e to the anti-sidetone condition. When however, a supervisor plugs into jacks 49 and 59 with a talephoneset,.not shown, but identical with that convsisting of receiver 46 and transmitter 56 this invention provides an arrangement whereby the aforementioned. balanced condition is removed, enabling supervisor and operator to converse. When'plugs are inserted into jacks 41 and 49 a circuit is closed for operating relay 25, which maybe traced from battery through the winding of relay 26, operated local. contacts of jacks 41 and 49, over normally closed contacts of a grouping key shown in Fig. 5 of'the before-mentioned copending application of Saul'and Shiel, Serial sistance 32 and condenser 3|, and accordingly, due to the unbalance resulting, the anti-side condition is removed and supervisor and operator may converse. If the operator should now operate the talk key 5 of a cord circuit and insert plug 62 into jack 63, relay 43 would operate as before described, releasing relay 26, which would reconnect the rear termination consisting of said resistance 32 and condenser 3 I reestablishing the normal anti-sidetone condition.

What is claimed is:

1. In a telephone system, a link circuit, an operators telephone circuit including a transformer having two windings, means for serially connecting each winding in a different conductor of said link, an impedance network normally connected across both corresponding ends of the two windings, an operators receiver connected between intermediate points of the two windings, a second receiver, means for connecting the second receiver in multiple with the operators receiver, and means responsive to the connection of said receivers in multiples to disconnect one of said networks from the transformer.

2. In an operators telephone circuit, a hybrid induction coil, a transmitter and receiver connected thereto, said coil being normally so balanced with respect to the connected transmitter and receiver that sounds afiecting the transmitter cause no corresponding effect in the receiver, a second transmitter and receiver, means for connecting the second transmitter and receiver to the induction coil in multiple with the first transmitter and receiver, and means responsive to said multiple connection to unbalance said coil.

' 3. In a telephone system, an operators cord circuit, a line connected thereto, an operators telephone circuit connected to the cord circuit, a source of ringing current, ringing means for connecting said source to the cord and then to the line, means responsive to the actuationof said ringing means for disconnecting said operators telephone circuit from the cord, and other means for delaying the reconnection of said telephone circuit to the cord for a predetermined interval after said ringing current has been disconnected.

4. In a telephone system, an operators'cord circuit, a line connected thereto, an operators telephone circuit connected to the cord circuit, a

source of ringing current, ringing means for connecting said ringing current to said cord and then to said line, means actuated when said ringing current is connected to the cord to disconnect said operators telephone circuit from the cord, and means for delaying the reconnection of said telephone circuit to the cord for a predetermined interval after said ringing current has been disconnected.

5. In a telephone system, an operators cord circuit, a line connected thereto, an operators telephone circuit connected to'the cord circuit, a source of ringing current, means associated with the cord circuit for causing said source of ringing current to be connected to the line, means responsive to the actuation of said ringing means for disconnecting said operators telephone circuit from the cord, and other means for delaying the reconnection of said telephone circuit to the cord for a. predetermined interval after said ringing current has been disconnected.

6. In an operators telephone circuit, a hybrid induction coil, a transmitter and receiver connected thereto, a balancing impedance connected to one terminal end of said induction coil,

a balancing impedance connected to the other terminal end of said induction coil, the connection of said balancing impedances causing said induction coil to be so balanced that sounds affecting the transmitter cause no corresponding efiect in the receiver, a second transmitter and receiver, means for connecting the second transmitter and receiver to the induction coil in multiple with the first transmitter and receiver, and means responsive to said multiple connection for disconnecting one of said balancing impedances so that said induction coil is thereby unbalanced and sounds affecting either or both of said transmitters are reproduced in both of said receivers.

GEORGE N. SAUL.

Images