US778599A - Telephone-exchange switchboard apparatus. - Google Patents

Description

' No. 778,599. PATENTED DEG.27,1904.

J. L. MOQUARRIE. TELEPHONE EXCHANGE SWITGHBOARD APPARATUS.

APPLIOATIOH FILED FEB. 1, 1902.

W/TNESSES'. INVENTOR.

UNITED STATES Patented December 27, 1904.

PATENT OEErcE.

JAh IES L. MOQUARRIE, OF CHICAGO, ILLINOIS, ASSIGNOR TO WESTERN ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A. CORPORATION OF ILLINOIS.

TELEPHONE-EXCHANGE SWITCHBOARD APPARATUS.

SPECIFICATION forming part of Letters Patent No. 778,599, dated December 2 7, 1904.

Application filed February 1, 1902. Serial No. 92,108.

To all whom it may concern.-

Be it known that I, JAMES L. MOQUARRIE, a citizen of the United States; residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Telephone-Exchange Switchboard Apparatus, of which the following is a full, clear. concise, and exact description.

My invention relates to apparatus for telephone-switchboards, and is applicable more particularly to a telephone-exchange system in which signals are automatically transmitted from the substation to the central office as the substation-telephone is taken for use or replaced on its switch-hook. In such systems a central battery is connected with all the lines through individual line-signaling apparatus operated by the flow of current in the line, which is determined by the open or closed condition of the telephone-switch at the substation. It has been common to provide a cut-off relay whose switch-contacts areinterposed between the battery and line-signaling apparatus and the line conductors, this relay being excited by current in a local circuit which is es tablished in registering contacts of the usual plug and spring-jack switch when connection is made with the line. Abattery has been connected with the plug-circuit to furnish current to the substation-transmitter for telephonic purposes and also for operating a supervisory signal temporarily associated with the line, this battery being applied to the line when connection is made therewith by inserting the plug-terminal of the cord circuit into the spring-jack of the line. An objectionable feature of this system has been that as the plug was inserted in the spring-jack the source of current would be rapidly connected and disconnected, due to the successive engagement of the difi'erent contact-pieces of the plug with the contacts of the spring-jack, the result being that a series of violent cracks or noises would be produced in the substation telephone which the subscriber is holding to his ear. These noises have been produced not only by the mere current from the battery itself, but also by the more violent induced currents caused by the induction of the repeating-coils in the plug-circuit.

My object has been to devise a system in which these noises produced in the substationtelephone as the connection is made with the line may be greatly reduced, the inductive disturbances heretofore caused by the discharge from the repeating-coil being entirely obviated. In my system when the subscriber takes his telephone to transmit a call a signal is automatically displayed at the central office, and simultaneously the whole line is shortcircuited until the operator in answering the call has completed connection therewith, whereupon the short circuit will be removed and the battery in the plug-circuit applied. Very little noise is produced by the connection of the battery, the disturbances Which have been most objectionable heretofore having been produced by the inductive action or kick of the coils in the circuit.

I will describe my invention in connection with the accompanying drawing, which illustrates the preferred embodiment thereof, and the features or combinations which I regard as novel will be pointed out in the appended claims.

The drawing illustrates diagrammatically two telephone-lines extending from substations to a central-office switchboard, the circuit of the operators switching apparatus for uniting the lines being also indicated.

Each line has two limbs 1 2, between which the substation apparatus is bridged in the usual Way, said limbs being connected at the central ofiice with the poles of the central battery b. The usual multiple spring-jacks a a are provided for each line, the short and long line springs a? of each spring-jack being connected, respectively, with the limbs 1 2 of the telephone-line for which the spring-jack forms a connection-terminal. Each springjack is also provided with a ringcontact or thimble a in accordance with the usual practice, and the thimbles of all the spring-jacks of each line are connected to earth by a conductor 3, which includes the magnet-winding of the cut-off relay (Z of such line. The cut.- ott' relay is provided with two armatures, each of which has a back contact against which it normally rests, these contacts being broken when the relay is excited. These contacts are interposed in the limbs 1 2 of the telephoneline between the spring-jacks of said line and the poles of the battery. The magnet-winch ing of the line-relay c is included in the circuit of limb 2 of the telephone-line between the free pole of the battery Z) and the contacts of the cut-off relay. \Vhen the cut-off relay is excited, therefore, the connection of the line with battery 6 and the line-signaling apparatus is broken. A line signal-lamp 0 is connected in multiple with the line-relay c. A conductor 4 extends from that armature of the eut-ofi relay (Z which is connected with the limb 2 of the line to the grounded pole of the battery b through normally open switchcontacts, which are controlled by the line-relay c, said contacts being closed by said linerelay when excited.

The usual telephone-switch is provided at the substation for controlling the line-circuit, and when this switch is once closed, as in transmitting a call, the line-relay c is excited and closes the circuit of conductor 4: directly to the grounded pole of the battery, shunting or short-circuiting the line. A local circuit is thus established, which includes the battery 6, the line-relay c, and the signal-lamp 0 in shunt thereof, the switch-contacts of the cutoff relay (Z, and the conductor 4, completed at the switch-contacts of said line-relay c. This local circuit is thus under the control of the cut-off relay (Z only and. will remain closed and the signal-lamp a lighted until the cut-ofl' relay is excited.

The central-office operator is provided with the usual pair of plugs f g, united by link conductors 5 6 of a cord-circuit, whereby any two lines may be connected together by inserting the plugs into the spring-jacks of such lines. Each plug is provided with the usual tip, ring, and sleeve contacts, which are adapted to engage, respectively, with the short and long line springs and the test-ring of the springjack, in which the plug may be inserted. The tip and ring contacts ff of the answering-plug f are connected with the corresponding tip and ring contacts g g of the calling-plug g by the conductors 5 6 of the plug-circuit, which include the windings of the usual repeating-coil. The central battery Z) is connected in a bridge of the plugcircuit between the windings of the repeatingcoil, the grounded pole of the battery being connected with the tip-strand 5 of the plugcircuit. A conductor 7 including a supervisory signal-lamp it and the magnet-winding of a relay 70, extends from the free pole of the battery Z) to the third contact or sleeve f of the answering-plug. A conductor 8,

including a supervisory signal-lamp Z2 and a resistance Z, connects the free pole of the battery b with the third contact or sleeve g of the calling-plug g. \Vhen one of the plugs is inserted in the spring-jack of a line, a local circuit, including the supervisory signallamp of such plug, is thus temporarily estal lished by the engagement of the third contact or sleeve otthe plug with the ring-contact a of the spring-jack, this circuit including the conductor 3 of the line whose spring-jack is plugged into, so that the cut-off relay (Z in the circuit of said conductor is excited. The usual supervisory relays m m may be included in the ring-strand 6 of the plug-circuit between the battery 6 and the ring-contacts of the plugs f and g, respectively, said supervisory relays controlling shunts about the signal-lamps Zt it, respectively, in accordance with the usual practice.

In accordance with my invention the con ductor 6 between the ring-contact f" of the answering-plug and the free pole of the bat tery b is normally open at the switch-contacts of the relay k, so that the battery 5 will not be applied to the contact f until the relay Zr shall have been excited by current flowing in the circuit 7 3. This relay Z; should be ad justed to act sluggishly, so that the ring-contact of the plug will not be connected to the battery until after the cut-off relay (Z shall have been excited and the short circuit A broken.

To review briefly the operation of the system, the subscriber transmits a call in the usual way by taking his telephone from its hook. The circuit of the line is thus closed and the current flowing through the line-relay 0 causes the same to draw up its armature, whereby the local signal-circuit is completed by way of the conductor 4:, which shunts or short-circuits the telephone-line and the substation appartus thereof. Current flowing in this local circuit maintains the relay 0 excited and causes the illumination of the signal-lamp 0, indicating to the operator that a connection is desired. The instant after the subscriber removes his telephone from its hook his line is thus short-circuited and remains so until the cut-0H relay (Z shall havebeen actuated. n The operator perceiving the signallamp c lighted responds to the call by inserting her answering-plugfin the answering spring-jack of the line. The ring-contactf of the blug being disconnected from the battery, current will not be applied to the test-ring a until the plug is inserted sufliciently to bring the sleeve f thereof into engagement with said test-ring. As soon as these two parts come into contact the circuit 7 3 is established, so that relays (Z and k are both actuated. The local circuit t is thus broken and the signaling apparatus disconnected from line, and the battery 6 in the plug-circuit is applied to the line by way 0 the spring-jack as soon as the relay Zu draws up its armature. The only noise that the subscriber hears in his telephone, therefore, is the single click when the relay 7t responds.

As usually constructed cut-off relays act rather sluggishly, and if the battery should be connected at all times with the ring-contact of the plug there might be a discharge of current from the battery I) in the plug-circuit through conductors 6 to the long-line spring of the jack, and thence through the conductor at to earth until the cut-off relay should respond. Then upon the breaking of this circuit by the cut-off relay the self-induction or kick of the repeating-coil in the plug-circuit would cause a violent disturbance on the line, making a disagreeable click in the subscribers telephone. By providing the relay 7r the battery is disconnected from the ringcontact of the plug until the circuit through the cut-ofi' relay is completed, and for the reasons above given I prefer that the relay/t should be, if anything, a little more sluggish than the cut-off relay (Z, so that the grounded branch & will surely be broken before battery is applied to the ring-contact of the plug.

\Vhile I have for convenience of illustration shown three batteries in the drawing, each marked .7), it will be understood that in accordance with the usual practice these may be one and the same battery.

Having thus described my invention, I claim as new, and desire to secure by Letters Patent, the following:

1. The combination with a telephone-line extending-from a substation to a central office, of a source of current in circuit with the line at the central oflice, a switch at the substation controlling the flow of current in the line, a line-relay at the central oflice in the path of current so controlled, a local circuitincluding said relay closed by said relay when excited, a portion of said local circuit shunting or short-circuiting the substation apparatus, a signal controlled by the iiow of current in said local circuit, a spring-jack for the line, a plug and plug-circuit for making connec tions therewitlnmeans actuated upon the insertion of the plug in the spring-jack for breaking said shunt or short circuit of the substation apparatus, a source of current associated w ith the plug-circuit, a switch it adapted to connect said source of current between the lineterminals of the plug, and means controlled by the insertion'of the plug in the springjack for actuating said switch, as described.

2. The combination with a telephone-line extending from a substation to a central office, of a source of current in the circuit of the line at the central office, a switch at the substation controlling the flow of current in the line, an

electromagnetic switch at the central office responsive to the flow of current controlled by the substation-switch and adapted when actuated to establish a short circuit of the line, a spring-jack for the line, a plug and plugcircuit for making connection therewith,mechanism actuated in establishing connection with the line for interrupting the short circuit, a source of current associated with the plug-circuit, and an electric switch controlling the connection of said last-mentioned source of current with the line actuated in establishing connection with the line, whereby the short circuit is interrupted before the application to the line of the source of current connected with the plug-circuit.

3. The combination with a telephone-line and a cord-circuit for making connections therewith, of the line-relay 0 adapted when actuated to providea local circuit through the same to temporarily short-circuit or shunt the line, the cut-off relay (Z with the relay is of the cord-circuit adapted to be connected in series, said relay is being also adapted to act as a switch when actuated, to throw current onto the line, immediately after the cut-off relay has acted to open said local circuit.

4:. In a telephone system, the combination with the cut-off relay of a line, of a sluggish relay it in the cord-circuit, and the centralized battery, said relay 7t acting as a switch to close said battery to line after the cut-off relay has acted, substantially as described;

5. The combination with a telephone-line extending from a substation to the poles of a central source of current, of a substationswitch controlling the flow of current in the line, a line-relay at the central office in the path of current so controlled, a line-lamp in shunt thereof, a local circuit including said line-relay and lamp in multiple branches thereof closed by said relay when excited, a portion of said circuit shunting the substation apparatus, a spring-jack for the line, a plug and plug-circuit for making connection therewith, means actuated upon the insertion of the plug in the spring-jack for breaking said shunt of the substation apparatus, a source of current in a bridge of the plug-circuit, an electromagnetic switch it controlling the application of said source to the line, and a circuit therefor completed in registering contacts of said plug and spring-jack.

In witness whereof I hereunto subscribe my name this 29th day of January, A. D. 1902.

JAMES L. MOQUARRIE.

\Vitnesse's:

D. E. WVILLETT, EDWIN H. SMYTHE.

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