US1287009A - Telephone-exchange system. - Google Patents

Description

W. H. HARRISON. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED MAY 9. 1918.

Patented Dec. 10, 1918.

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WILLIAM H. HARRISON, OF BROOKLYN, NEW YORK, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCOR?ORATED, OF N EVJ YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Application filed May 9, 1918.

To all iv/1.0772, it may concern:

Be it known that I, WILLIAM H. HARRI- SON, a citizen of the United States, residing at Brooklyn, in the county of Kings, State of New York, have invented certain new and useful improvements in Telephone-EX- change Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems, and more particularly to such systems employing trunkcircuits over which connections between telephone "lines terminating at different switchboards may be made.

The object of this invention is to provideimproved signaling means for systems of,

, this invention, reference should be had to the following description, considered in connection with the accompanying drawing illustrating one embodiment thereof.

As shown in the drawing, a trunk circuit A extends from a first switchboard X to a second switchboard Y. At the switch board X there is located a cord circuit B, by means of which connection may be made between a telephone line (not shown) terminatin at switchboard X and the trunk circuit A. A cord circuit C provided at the switchboard Y may be employed for connecting the trunk circuit A with an exten sion line represented by the jack D, or with a trunk circuit (represented by jack 11) extending to a central office. The extension telephone line D and the trunk circuit E are preferably of the types disclosed in the patent to H. L. Darrah, No. 1,232,5OZ, with this difference, that the sleeve contactof the jack of the extension line D has no ground connection and the sleeve contact of the 1 Specification of Letters Patent.

Patented Dec. 10, 1918.

Serial No. 233,449.

jack of the trunk circuit E has a ground instead of a battery connection.

The cord circuit C may also be employed to interconnect extension lines or to connect an extension line with the central oflice trunk circuit. The apparatus shown to the left of the dotted line, 22, may be located at the switchboard X, and that shown to the right of the dotted line 3-3, at the switchboard Y.

The. operator at switchboard X desiring to establish a connection with or through the switchboard Y may insert plug 5 of the cord circuit B into jack 6 of the trunk circuit A, whereupon lamp 7 is lighted and relay 8 operated over a circuit from battery through the normal contact of the listening key 9, contact of supervisory relay 10, lamp 7, sleeve contacts of the plug 5 and the jack 6 and the winding of relay 8 to ground. Relay 8, in operating, causes the operation of a slow-release relay 11, the function of which will more fully hereinafter appear. Relay 12 also operates upon the connection of the plug 5 with the jack 6. The operator may now actuate ringing key 13 to cause the operation of relay 15 over a circuit from a source of ringing current 16 through the lower alternate contact of ringing key 13,

ring contacts of the plug 5 and the jack 6, condenser17, winding of relay 15, tip contacts of the jack 6 and'the plug 5, contact of relay 12 and the upper alternate contact of ringing key 13 to ground. Relay 15, in operating, causes the operation of relay 18, which connects a second source of ringing current 19 in circuit with and operates an electromagnetic drop 20, the shutter 21 of which falls to furnish a signal. The restoration of the ringing key 13 to normal position causes the release of relays 15 and 18 and the disconnection of the source 19 from the trunk circuit. The operator at switchboard Y, observing the operated condition of the drop 20, may insert plug 30 of the cord circuit G into jack 31 of the trunk circuit A, where upon a slow-release relay 32 operates over a circuit from batterv through the winding of relay 32 and local contact 33 of the jack 31. After inserting the plug into the jack, the operator may restore the shutter 21 of the drop to its normal position. Relay 34 of the cord circuit C, and relay 35 of the Lit) trunk circuit Ado not operate. Relay 32, in operating, connects a marginal relay 36 inbridge of the trunk circuit A, and establishes a short circuit about the winding of the drop 20. This short circuit may be traced from the point 37 through the normal contact of the slow-release relay 38 and contact 39 of relay 32 to the point 40. The drop 20, by being short-circuited, is thereby operatively disconnected from the trunk circuit, and is prevented from operating after its shutter has been restored by the operator. \Vith this short circuit about the drop, .the drop is not operated by currents induced in the left-hand windings of repeating coil 41,

resulting from the closure and opening of circuit including the right-hand windings of this repeating coil.

The connection of the marginal relay 36 in bridge of the trunk circuit causes. the operation of a trunk relay 42 over a circuit from battery through the lower right-hand winding of repeating coil 43, lower normal contact of relay 18, lower left-hand winding of repeating coil 41, winding of-relay 36, contact 44 of relay 32, upper left-hand winding of repeating coil 41, upper normal contact of relay 18, upper right-hand winding of repeating coil 43 and both windings of relay 42 to ground. Trunk relay 42, in operating, causes the operation of relay 45, which connects relay 46 in bridge of that end of the trunk circuit which terminates at. the switchboard Y. Supervisory relay 10 is thereuponoperated over a circuit from battery through the lower winding of" re tardation coil 48, winding of supervisory relay 10, lower normal contact of ringing key 13, ring contacts of the plug and the jack 6, lower left-hand winding o'f repeating coil '43, lower contact of relay 45, winding of relay 46, upper contact of relay 45 and the normal contact of relay 46 to ground. Supervisory relay 10, in operating, causes the efiacement of the supervisory lamp 7 which mayselve as a signal to the originating operator that the distant operator has answered. The operator at switchboard X may then actuate listening key 9 to connect the telephone set with the cord circuit B. Relay 46 also operates, establishing a short circuit for the lower winding of re lay 42, thereby reducing the resistance in circuit with themarginal relay 36 which now operates. Upon the operation of relay 46, the energizing path for relays and 46 from the point 22 then continues to ground by way of the upper left-hand winding of repeating coil 43, tip contacts of the jack 6 and the plug 5, the contact of relay 12, upper normal contact of ringing key 13 and the upper winding of retardation coil 48. Relay 36, in operating, establishes operating circuits for slow-release relay 38 and lockup relay 50. Relay 50, in operating, establishes a locking circuit for itself from batincluded in shunt of the winding of the drop This resistance is low enough to prevent the operation of the drop upon the discharge of either of the condensers 24 or 25. The drop, therefore, remains operatively disconnected from the trunk circuit.

The operator at switchboard Y may now actuate listening key 51 to connect the operators telephone set with the trunk circuit. Since the operators telephone set at the switchboard X .is already connected in circuit, the two operators may converse. It connection is to be established with an extension line, the operator at switchboard Y may insert plug 52 into the jack D, and may then actuate a ringing key (not shown) to connect with the extension line ringing current for operating the usual call bell. .Upon response of the subscriber on an extension line, the line circuit is closed in the usual manner, whereupon the annunciator is actuated to furnish a signal indicating to the operator that the subscriber has respond ed. This annunciator 53 furnishes a signal while the subscribers are talking, and does notdisplay'a signal when the subscriber has restored the receiver to the switchhook.

If connection is to be established with a line terminating at a central oflice (not shown) the operator at switchboard Y may then insert the plug 52 into the jack E, whereupon relays 34 and operate in parallel by way of the grounded sleeve contact of the jack of trunk circuit E. The opera- 'tion of these two relays disconnects battery for talking purposes from both the trunk and the cord circuit. As is usual when connectlon 1S established over a central office trunk circuit between a private branch eX- change telephone line and a central oiiice telephone line, battery for talking purposes is furnished from the central otlice. The operation of relay 34- connects retardation coil 54 in bridge of the talking strands of the cord circuit, and relay 35, in operating, connects a resistance 55 in bridge of the talking conductors of the trunk circuit, thereby establishing a circuit for the usual line relay connected with the central oiiice end of the trunk circuit.

If the operator at switchboard Y, after inserting plug 30 into the jack 31, does not operate the listening key 51, the operator at switchboard Y may desire to re-ring the operator at switchboard Y. This may be done by withdrawing the plug 5 from, and then reinserting it in, the jack 6. Upon the withdrawal of the plug from the jack, relay 46 releases its armature, thereby opening the short circuit about the lower winding of relay 42. The resistance in circuit'with marginal relay 36 is thereby increased, causing the release of this relay'36- Upon the release of relay 36, the drop 20' isenergized over a circuit from battery through the leftf hand lower winding of repeating coil 43,

lower normal contact of relay l8 and lower left hand winding of I repeating coil .41, winding of the drop 20, alternate contact of slow-release relay 38, left-hand alternate contactof relay 50, normal contact of relay 36 and contact 33 to ground. The energiza? tion of drop 20 causes the attraction of the armature of the drop, .which' releases the shutter 21 to furnish a signal. The closure of this operating circuit of this drop20 but momentary, for relay38, which is ofthe slow-release type, begins to release its armae ture immediately upon the release" of the marginal relay 36. U on the withdrawal of the plug 5 from the jack 6, relay 8 is deenergized, and relay 26 is energized over a.

path from battery through the normal contact of relay 8, winding of relay 26, .normally closed cont-act of the jack 6, upper left-hand winding of the repeating coil 43, upper contact of relay 45 and the normal contact of relay 46 to ground, Since relay 11 is of the slow-release type, the lower contact of relay 26 is closed before the lower alternate contact of relay 11 is opened, whereby a locking circuit for relay 11 is completed. The lighting of the lamp27 to furnish a false signal is thereby prevented. The reinsertion of the plug 5. within the jack 6 causes the energizati'on of relay 46,

from the jack 6 causes the deenergization of relays 8 and 46, and the energization of relay 26. causes marginal relay 36 to release its armature, as before described, ,to momentarily close an. operating circuit for the drop 20, which permits its shutter 21 to fall to display a disconnect signal. This shutter 21 may be restored to its normal position be.- fore the operator at the switchboard Y withdraws the plug 30. from the jack 31. In withdrawing the plug 30 from the jack 31, condenser 28 may be discharged, or a battery circuit including the right-hand windings of repeating coil 41 may be opened or closed. In either event, the resulting flow of The deenergization of relay 46v current through the repeating coil windings induces a current in the left-hand wmdings thereof, whereuponthe condensers 24 and 25 may discharge. The drop 20, therefore, remains operatively disconnected from the trunk circuit until after the condensers have been discharged, in orderthat there may be no false operation of the drop; The

operative'disconnection of the drop 20 from the trunk circuit is thus maintained, due to slow-release relay 32, which, for an a preciable time after the disconnection o the plug from the jack, holds closed the shunt circuit has assumed its normal condition.

Should a call originate atthe switchboard Y and connection for completion over the. trunk circuit A, the insertion of the plug 30 into the jack 31 causes the operation of relay 32. Relay 36 is thereby bridged across the talking strands of the trunk circuit, whereupon relay 42 operates over a circuit from battery through the lower right-hand winding :of repeating coil 43, lower normal contact of relay 18, lower left-hand winding of repeating coil 41, winding of relay 36, contact 44 of relay 32, upper left-hand wind.- ing of repeating coil 41, upper normal contact'o'f relay 18, upper right-hand winding of repeating coil 43 and the two windings of relay 42 to ground. Relay42, upon op erating, causes thev energization of relay 45. Upon being energized, relay 45tcauses, the

operation of relay 26 overa circuit from bat tery through the normal contact of relay 8, winding of relay 26, normally closed contact of the jack 6, upper left-hand winding of repeating coil 43, upper contact of relay 45 and the normal contact, of relay 46 to groundf Relay 26, in operating, completes a circuit over which the lamp 27 is lighted, to furnish a signal to the operator at the switchboard X.

The operator at the switchboard X, upon observing the lighted condition of the lamp 27, inserts theplug 5 into the jack 6, where upon relay 8 operates and relay 26 releases,

eflacing the lamp 27. Relay 8, in operating,

causes the operation of slow-release relay 11 as beforedescribed. Relay 46 now operates and short-circuits the lower winding of relay 42, thereby permitting the operation of relay 36. Relay 36, in operating, causes the operation of slow-release relay 38 and lockup relay 50. The latter, in operating, closes a locking circuit for itself through its righthand alternate contact and contact 33 of'the v jack31.

forethe other operator, thev withdrawal of the plug 30: from the-jack 31 causes the re -i leaseof relays 32,38, 50, andfl2. Relay 42, in releasing, causes the release. of relay 4L5'followed by the release of relays l6 and e 10, whereupon thesupervisory lamp 7 lights to furnisha disconnect signal to the opera;

' tor at switchboard X, a Since relay 38zisnow released and its alternate contact is open,

therewill be no. false operation of the drop 20 upon the withdrawalof; the plug 5 from the jack 6. I g a What isclaimed'is; k e a a l; A telephone exchange systemcomprising a trunk circuit extending from a first to a second switchboard, a link circuit at the, first switchboard connected with the trunk circuit, a signaling device at the second switchboard normally. operatively asso ciated with the trunk circuit, a source ofsignalingcurrent, means in the link circuit for connecting the source of signaling current withthe trunk circuit for causing the operation of the signalingdevice, a link circuit at the second switchboard, means responsive to the connection of the second link circ li. with the trunk circuit for operaa tively disconnecting the signaling device therefrom, and,v means responsive to, the disconnectlon of the, first link circu t from the trunk circuit for operatively associatingthe signaling devicewith the trunk circuit and for causing theoperation thereof.

2. A telephone exchange system comprising a trunk. circuit extending from a first to a second switchboard, a link circuit at the first switchboard connected with the trunk circuit, a signaling deviceat the second switchboard normally operatively associated with the trunk clrcult, a source of signaling current, means in the trunk circuit for connecting the source ofsignaling current with the trunk circuit for causing the operation of the signaling device, a link circuit at thesecondswitchboard, a normally open shunt circuit for the signaling device,

a relay energized upon the connection of the second link circuit with the trunk circuit for establishing the shunt circuit about the signaling device, and a relayresponsive to the disconnection of the first link circuit from the trunk circuitfor, completing an operating circuit throughcthe signaling device. a

3. A telephone exchange system comprising a two-conductor trunk circuit extending from a first to a second switchboard, a link circuit atthe first switchboard connected withthe trunk circuit, a signaling device at the second switchboard normally operatively associated with the trunk circuit, a source of signaling current, means in the link circuit for controlling the connection of the source of signaling current in circuit with the two conductors of the trunk circuit and the signaling device thereby to operate the signaling device, a link circuit at the second switchboard, an operating circuit for the signaling device including one of the conductors of; the trunk circuit, means responsive to the connection of the second link circuit with the trunk circuit for partially establishing the operating circuit, and means responsive to the disconnection of the first link circuit from the trunk circuit for completing the partially established operating circuit;

4. A telephone exchange system comprising a two-conductor trunk circuit extending from a first to. a second switchboard, alink circuit at the first switchboard connected withthe trunk circuit, a signaling device at the second switchboard normally operatively associated with the trunk circuit, a source of signaling current, means in the link circuit for controlling the connection of the source of signaling current in circuit with the two conductors of the trunk circuit and the signaling device thereby to operate the signaling};v device, a link circuit at the second switchboard, a relay energized upon the connection of the second link circuit with the trunkcircuit, a second relay bridged across thetwo conductorsof the trunk circuit upon the energization of the first, relay and operating thereover, a slow-release relay energized upon the operation of the bridged relay, a relay in the trunk circuit responsive to the disconnection of the first link circuit from the trunk circuit for causing the release of the second relay, and an operating circuit for the signaling device completed upon the release of the second relay and including a contact of the slow-release relay.

5 A telephone exchange system comprising a two-conductor trunk circuit extending from a, first to a second switchboard, a link circuit at the first switchboard connected with the trunk circuit, a signaling device at the second switchboard normally operatively associated with the trunk circuit, a source of signaling current, means in the link circuit for controlling the connection of the source of signaling current in circuit with the two conductors of the trunk circuit and the signaling device thereby to operate the signal-, ing device, a link circuit at the second switchboard, an operating circuit for the signaling device including one of the conductors of the trunk circuit, a relay in the trunk circuit responsive to the connection of the second link circuit therewith for partially establishing the operating circuit, and a relay responsive to the disconnection of the first link circuit from the trunk circuit for completing the operating circuit.

6. A telephone exchange system comprising a trunk circuit extending from a first to a second switchboard, a source of signaling current at the first switchboard, means there at for connecting the source of signaling current with the trunk circuit, a signaling device in the trunk circuit responsive to the connection of signaling current therewith, a link circuit at the second switchboarch means in the trunk circuit responsive to the connection of the link circuit therewith for open atively disconnecting the signaling device from the trunk circuit, and switching means responsive to the opening of the trunk circuit at the first switchboard and cooperating with the second mentioned means for causing the operation of the signaling device.

7. A telephone exchange system comprising a trunk circuit extending from a first to a second switchboard, a link circuit at the first switchboard connected with the trunk circuit, a signaling device at the second switchboard, a source of alternating current, means in the link circuit controlling the connection of the source of alternating current with the trunk circuit for operating the signaling device, a link circuit at the second switchboard, means responsive to the connection of the second link circuit with the trunk circuit. for rendering the signaling device non-responsive to alternating current, a source of direct current, and means responsive to the disconnection of the first link circuit from the trunk circuit for connecting the source of direct current in circuit with the signaling device.

8. A telephone exchange system comprising a trunk circuit extending from a first to a second switchboard, a link circuit at the first switchboard connected with the trunk circuit, a signaling device at the second switchboard, a source of alternating current, means in the link circuit controlling the connection of the source of alternating current with the trunk circuit for operating the signaling device, a link circuit at the second switchboard, a relay in the trunk circuit responsive to the connection of a second link circuit therewith for rendering the signallng device non-responsive to alternating current, a source of direct current, and a relay responsive to the disconnection of the first link circuit from the trunk circuit for connecting the source of direct current in circuit with the signaling device to cause the operation thereof.

, 9. A telephone exchange system comprising a trunk'circuit extending from a first to a second switchboard, a link circuit at the first switchboard connected with the trunk circuit, a signaling device at the second switchboard, a source of alternating current, means in the link circuit controlling the connection of the source of alternating current with the trunk circuit for operating the signaling device, a link circuit atthe second switchboard, a relay in the trunk c'ircuit responsive to the connection of the second link circuit therewith, a source of direct current, a relay responsive to the disconnec tion of the first link circuit from the trunk circuit, and an operating circuit for the sig naling device and a source of direct current established upon the response of the second relay and including contacts of both relays.

10. A telephone exchange system comprising a trunk circuit extending from a first to a second switchboard, a link circuit at the first switchboard connected with the trunk circuit, a signaling device at the second switchboard, two sources of current of different character, means in the link circuit controlling the connection of one of the sources of current with the trunk circuit for operating the signaling device, a link circuit at the second switchboard, means responsive to the connection of the second link circuit with the trunk circuit for operatively disconnecting the signaling device from the trunk circuit. and means responsive to the disconnection of the first link circuit from the trunk circuit for connecting the other source of current in circuit with the signaling device.

11. A telephone exchange system comprising a trunk circuit extending from a first to a second switchboard, a link circuit at the first switchboard connected with the trunk circuit, a signaling device at the second switchboard, two sources of current of different character, means in the link circuit controlling the connection of one of the sources of current with the trunk circuit for operating the signaling device, a link circuit at the second switchboard, means responsive to the connection of the second link circuit with the trunk circuit, a normally ineffective operating circuit for the signaling device and the other of the two sources of current, and means responsive to the disconnection of the first link circuit from the trunk circuit and cooperating with the other responsive means to render the operating circuit effective for causing the operation of the signaling device.

12. A telephone exchange system comprising a trunk circuit extending from a first to a second switchboard, a link circuit at the first switchboard connected with the trunk circuit, a signaling device at the sec- 0nd switchboard, two sources of current of different character, means in the link circuit controlling the connection of one of the sources of current with the trunk circuit for operating the signaling device, a link circuit at the second switchboard, a relay energized While the second link circuit is connected with the trunk circuit, a relay dot-Energized upon the disconnection of the first link circuit from the trunk circuit, and an operat- 10 In Witness whereof, I hereunto subscribe 15 my name this 3rd day of May A. D., 1918.

VVILLIAM H. HARRISON.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. 0.

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