US816078A

US816078A - Telephone-exchange system.

Info

Publication number: US816078A
Application number: US7092401A
Authority: US
Inventors: William M Davis
Original assignee: Stromberg Carlson Telephone
Current assignee: Stromberg Carlson Telephone Manufacturing Co
Priority date: 1901-08-05
Filing date: 1901-08-05
Publication date: 1906-03-27
Anticipated expiration: 1923-03-27

Description

. PATBNTED MAR. 27, 1906.

; W. M. DAVIS.

TELEPHONE lXgANGrE` SYSTEM.

APPLICATIONv FILED AUG.5.1901.

UNTTED STATES PATENT @Finca-.

vWILLIAM DAVIS, CHICAGO, ILLINOIS, ASSIGNOR, BY MESN ASSIGNMENTS, TO STROMBERGr-OARLSON TELEPHONE MANUFAO= TURING COMPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

, vTELEPHONE-'Excl-IA'NGE SYSTEM. l

Specification of Letters Patent.

Patented March 27, 1906.

Application led August 5,1901. Serial No. 70,924.

To au 'wh/om it ,may concern: Be it known that I, WILLIAM M. DAVIS, a `Citizenof the United States, residing at Ohicago, in the county of Cook and State of Illinois, have invented a certain new and usefulv Improvement in Telephone-Exchange Sys-Y call to interrupt the circuit including the linerelay, whereby the line-indicator is rendered inactive.V Heretofore for the purpose of con-v trolling the operation ofthe cut-,off relays.

the cordcircuit. has been equipped with a third cord=strand terminating inl a third contact part carried by the plug, which third contact part constituted one terminal of the cir-v cuit, including the cut-off relay, the other ter- IrlI'lal usually residing in a metallic' thimble located before the jack. I t is an object of my invention to equipa relay switchboard in a manner to dispense with this third conductor,

feature of the invention may be employed in connection with all types of multiple boards employing relays ,for controlling the line-indicators.

A second feature of the invention relates particularly to multiple switchboards, and consistsin means whereby the thimbles of the sprin jacks of each subscribersline arevv connecte in a test-circuit immediately upon the removaliof the receiver at the calling subscribers station, are preventedfrom e'ec'ting connection with a, calling subscriber with whom another subscriber may desire connection, even though the callingv subscriber has not been answered by hs'operator. As is well known, test-thimbles are usually not charged with test-batte13T Y orotherwise operatively associated with the Bythis means operators test-circuit until the calling subscriber has been answered. vAs the operators may defer plugging into the jacks of calling subscribers until their connections have been completed, an interval may arise in which there are no `means of determiningthe condition of the calling-subscribers line as this line may'then be tested Not busy, so that the callingsubscriber may then undesirably be ,connected with another calling subscriber wishing oo nnection withhim.

I practice the first feature of my invention by providing switching apparatus that serves to include the heliX'ofthe cut-0E relay in bridge of the telephone-line, in which bridge is preferably included a source of current. A relay is preferably provided whosey armav'ture in its normally unattracted position serves momentarily toy close circuit through vthe cut-off relay, not by including this relay in bridge of the telephone-line, but momentarily establishing a local circuit therefor as the plug enters the jack, the armature of the re. lay being includedin this local circuit. When the plug has been fully inserted within the l jack, the latter relay is operated to open the local circuit; vbut the cut-off relay, having been previously ener ized to include the same in bridge of the telep one-line, remains in this relation to the line until the plug is withdrawn.

In practicing the second feature of In invention, which is designed for multipleswitchboard telephone-exchange systems, I employ a relay, which may be theaforesaid line-relay, and provide a switch.` to be .controlled thereby, which is operated'when a subscriber operates the said relayy upon removing his receiver from its hook' toconnect testing-battery lwith' the` test contacts or thimbles of the spring-jacks of the said' line upon the various sections of the multiple board. The operator thus does not control" the charging of the test-thimbles, thiscontrol being effected by thejcalling subscriber'.V

I will explain my invention more fullyY by reference to the accompanying drawing, in which the figure is a diagrammatic viewillustrating a telephoneexchange system embodying the features of my invention.

At the substations and 120 are illustrated IOO well-known types of telephonie apparatus.

At each station there is provided a'signal-re-- ceiver 1, a telephone-transmitter 2, a primary winding 3, and a switch-hook 4 for including the bell 1 in circuit when the receiver 5 is in .place upon the hook and for excluding this bell from circuit and including instead thereof the transmitter 2 with the primary winding 3 when the receiver is removed from its hook.

There is included in a local circuit with the receiver 5'the secondary 6 of a transformer. Other types of telephone-station apparatus, however, may be employed without departing from the spirit of my invention. yTelephone-lines extend by their limbs 7 and 8 to the armatures 9 and 10 of a cut-off relay 11. The limb 7 then extends when the armature 9 is, in engagement with its normal contact through the winding of the line-relay 12 to one terminal of the common battery 13, in this instance the positive terminal, the limbs 7 thus when idle having common connection with this terminal of the battery. The limb 8 byreason of the engagement of the armature with its normal contact is normally connected with the remaining terminal ofthe common battery. Thus the common battery is normallyin bridge of the telephonelines but the condensers 15 at the substations prevent the flow of this battery by way of the telephone-lines when the telephone-receivers are upon their switch-hooks.

When a subscriber initiates a call by removing his receiver from its telephone switch-hook, the common battery 13 is closed through the winding of the relay 12, which thereupon attracts its armature, thereby uniting the contacts 16 17 to actuate the corresponding line-indicator 18, that is thus included in a local circuit with the common battery, and also closes the contacts 19 and 20 together, whereby one terminal of the common battery, in this instance the positive terminal, is connected with the test-thimbles 21 of the spring-jacks 22, distributed over the various sections of the multiple switchboard.

Itwill be observed that the tes't conditions are automatically supplied by the calling subscriber when he removes his telephone from the switch-hook. The test-controlling mechanism operated by the subscriber is thrown out of service when the operator answers his call 5 but the test conditions are immediately restored through the agency of the sleeve of the answering-plug engaging the test-thimble of the jack and including the common battery. The test of course is manifested upon the depression of the operators listening-key if the line tested elsewhere is busy.

Thus is one object of my invention accomplished-namely, the immediate fulfilment of busy-test conditions for the calling-subscribers line to prevent interference thereof after a call is initiated.

The short line-springs of the various springjacks are adapted for connection with the limb 8, while the long line-springs are adapted for connection with the limb 7, these springs being also connected with the testthimbles. Cord-circuits are employed, one of which is illustrated, comprising in this instance answering and connecting plugs 23 24, the tips whereof are united by a tip-strand, while the sleeves are united by a sleevestrand that includes in circuit therewith the operating helices of supervisory relays 25 26, a bridge-conductor 27 being included between these helices and including an inductive resistance 28, whereby the control of these supervisory relays may be independently effected by the corresponding subscribers apparatus. Each supervisory-relay core is provided with a supplemental winding 29, these supplemental windings being included in a closed local circuit. These supervisory relays control the supervisory signals 30 31 by means of their armatures 32 33.

As a result of the manipulation of the apparatus to be hereinafter set forth contacts 34 35 are closed to complete a cord-circuit, the armature 33 effecting this engagement of the contacts and disrupting the test-circuit, including the testing-conductor 36, which forms the subject-matter of my Patent N o. 697,991, issued April 22, 1902.

It will be seen that when a subscribers line is busy a connection is eii'ected between the positive terminal of the battery 18 and the thimbles 21 of the spring-jacks 22, which connection is completed through the winding of the relay 12, the armature 20, and the contact-anvil 19. This condition lasts during the interval of time that elapses when the subscriber takes his receiver oid the switchhook and until connection is eiiected by means of a plug. When connection is effected, the thimble 21 is still connected to thc positive battery-terminal, but now receives its current directly from the sleeve of the plug 24, which is directly connected to the positive terminal of the battery 13 through the primary winding of the relay 26 and the inductive resistance 28. It will thus be apparent that the thimble 21 has at all times positive connection with the source of current when the line is in use. The calling side of the cord-circuit terminating in the plug 24 is used in making a test to ascertain whether a subscribers line is busy. As this )lug 24 has not been inserted in the spring-jac {of the called subscriber, the repeating coil-relay 26 is not energized and the switch is in its unattracted condition, not engaging its alternate contact anvil 34. The operator in making the test applies the tip of the plug 24 to the thimble 21, and if the subscribers linel is busy it will be apparent to the operator, as a circuit is completed through the various connections and instrumentalities as follows: from the positive pole of the battery 13, in

IOO

siente tery 13 and the operators head-receiver, may be effected when the tip of the plug 24 comes in contact with the thimble 21,-if the line is busy. If no cliclris apparent-that is,

if no circuit is Jformed around the battery 13- when the said plug touches the thimble 21, the line is not busy, as the thimble 21 is then normally disconnected from the battery. The switch 35 serves to close the normally disrupted tip-stand of the cord-circuit when the called subscriber removes his receiver, the purpose of keeping the tip-strand open until the parties are ready for conversation being solely to avoid occasioning a disagreeable click in the receiver of the calling subv scriber while making a test. It will be apparent that il? the tip-strandis not kept open while a test is being made a portion of the current will be diverted through the lsubscribers line `to the negative terminal of a battery instead of -being constrained, as in the present case, to flow altogether through the head-telephone of the operator. .A condenser 38 is employed, so` that the testcurrent, which may be madel small, if desired, will not flow through the secondary ofthe operators induction-coil, but will flow through the head-receiver. The cut-off relay 11 is in this instance connectedwith the short line-springs `at one terminal and with one pole of the common battery at the other terminal.. The remaining pole of the common battery is connected with the tip-strand of the cord-circuit by wayof the clearing-out or supervisory indicator l30 or 31 corresponding to the particular line, these connections beingv effected by the armatures 32 and 33 when they are unattracted, so that when a plug is inserted within a jack a local circuit is momentarily closed, which may be traced (taking the line of subscriber 120, for instance) from the short line-spring of the engaged jack, through the winding of the cut-0H relay, the common battery, the armature 33, its normal contact, the supervisory indicator. 31, to the'tip-strand and the tip of the plug engaging the short line-spring. Immediately the corresponding relay 26 is energized, disconnecting thelamp 31 from the tip-strand, the winding of the cut-off relay being then included in bridge of the telephone-lines, which parallel relation of the cut-oil magnet is maintained until connection between the subscribers is broken.

The parallel connection of the cut-oli relay 11 may be traced from the tip side of the cord-circuit which is connected with one terminal of the helix of said cut-0H magnet by the 'engagement of the tip of the inserted plug with the short line-spring, the other terminal ci the magnet 11 being connected with v the sleeve side oi the cord-circuit through the battery 13 and the inductive resistance 28. This will be readily apparent Jfrom the drawing, as the :only connection between the telephone-lines and the negative terminal of the battery when said lines are united for conversation is completed through the winding of the relay 11, each of the short line-springs of the two talking subscribers being furnished with negative current from the'b'attery,while said line-springs are at the same time metallically connected through the tipstrand oi the cord-circuit, which practically short-circuits the two springs and places the two relays 11 in parallel between the negative terminal oi the battery and the said tipstand, thebattery being included in a bridge oi said cord-circuit. Thus by means of very much simpliiied apparatus I am enabled to effect a control of the cut-off relay, Jfor which hitherto it was customary to employ `a third cord-strand and a special circuit.

While I have herein shown and particularly described the preferred embodiment of my invention, it is obvious that changes may be made without departing from the spirit thereof, and I do not, therefore, wish to be limited to the precise disclosure herein set Jforth; but,

Having thus described my invention, I

claim as new and desire to secure by Letters Patenti 1. In a'telephone-exchange system, the combination with a telephone-line extending from a subscribers substation to a central exchange, a plurality of spring-jacks of a multiple switchboard normally disconnected 'from the line-limbs, a single common source of current at the central exchange, a line-relay normally connected with the line-limbs through said source of current, a cut-oli relay having al single winding, one terminal of said cut-off relay being connected with one terminal of said source and normally with one line-limb, the other terminal of the cut-oil relay being connected with spring-jack contacts, a cord-circuit for connecting telephonelines together,l actuation of substation apparatus causing energization of said line-relay independently of the cut-off-relay winding, and means upon connection `oi said cord-circuit'with one oisaid multiple sections for closing a local circuit containing said cut-offrelay winding and said source of current whereby said cut-off relay is energized to disconnect. said line-relay Jfrom circuit, and lto connect the spring-jack contacts with the line-limbs', said local circuit including one of f the cord-circuit conductors and one limb oit' the telephone-circuit. y l

2. In a telephone-exchangev system, the combination with a telephone-line extending les - from a substation to a central exchange, of a plurality of multiple spring-jacks at the central exchange normally disconnected from the line-limbs, a single source of current at the central exchange for supplying both talking andsignaling currents, a line-relay, a cutofi' relay controlling said line-relay, one terminal of said line-relay being permanently connected with one pole of said source, and the other terminal of the line-relay being normally connected with one line-limb independently of the cut-oli-relay winding, actu ation of substation apparatus causing a circuit to be completed through said line-relay4 and source,.one terminal of said cut-oil-relay winding being permanently connected with one pole of said source, the other terminal of said Winding being normally connected with a contact of each ofthe multiple spring-jacks, and two strand cord-circuits for connecting telephone-lines together, one of said strands being normally connected with one pole of said source, connection of said cord-circuit with the spring-jack causing a local circuit to be closed through said cut-oiI-relay winding, said'source of current, said cord-strand and said spring-jack whereby said line-relay is rendered inert, a relay for controlling said local circuit, the second cord-strand being also connected with the same pole of said source through the winding of said relay controlling said local circuit, connection of said cord-circuit with a spring-jack causing closure of a circuit including said winding, said source of current, said second cord-strand, said spring-jack, said cut-off-relay winding and the telephone line-limbs and substation apparatus.

3. In a telephone-'exchange system, the combination with a telephone-line extending from a subscribers station to a central exchange, of a plurality of multiple spring-j acks at the central exchange, a single source of current at the central exchangefor supplying talking and signaling currents, a line-relay, a line-indicator governed by actuation of substation apparatus causing actuation of said line-relay, a cut-off `relay having a single winding for excluding the linerelay from circuit, cord connecting apparatus for connecting subscribers for conversation, a local circuit closed by the answering said line-relay,

plug or switch of the cord-circuit upon connection of the cord-circuit with a springjack, said local circuit including the cut-oil'- Vrelay winding, said source of current, a telcphonic portion of the cord-circuit and a con ductor portion constituting a continuation of the telephone-line, a switch included in said local circuit, and a relay in the cord-circuit for operating said switch, actuation of substation apparatus causing closure of the eircuit through said relay whereby said switch is connected to open the local circuit, the circuit through said relay including the windin g of said cut-ofi` relay whereby said line-relay is maintained inoperative. i

4. In a telephone-exchange system, the combination wi th a telephone-line extending from a substation to a central exchange, multiple spring-jacks at the central exchange normally disconnected from the line-limbs, a common source of current at the exchange for supplying talking and signaling currents, a line-relay, a line-indicator governed thereby, said line-relay being adapted for operation Athrough the agency of the apparatus at the substation, a cut-oiil relay having a single winding for excluding the line-relay from circuit, cord connecting apparatus for uniting subscribers for conversation, connection oi the cord connecting apparatus with a springjack causing closure of a local circuit, said local circuit serially including the entire cut-oilrelay winding, a telephonie portion of the cord-circuit, and a conductor portion constituting a continuation of the telephone-lin e,

a switch included in said local circuit, and a relay in the cord-circuit for operating said switch, actuation of substation apparatus causing the closure of the circuit through said relay whereby said switch is actuated to open the local circuit, said second circuit serially including said source of' current, said cut-off-relay winding, a cord-circuit conductor and said line-limbs and substation apparatus.

In witness whereof I hereunto subscribe my name this 13th day of July, A. D. 1901.

WILLIAM M. DAVIS.

Witnesses:

GEORG-E L. CRAGG, HERBERT F. OBERGFELL.