US253316A - Island - Google Patents

Description

B. SCOTT. TELEPHONE EXGHANGE SYSTEM AND APPARATUS.

No. 253,316. Patented Feb. A1882.

SUBSCRIB-ERS STATIONS.

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UNITED STATES PATENT OFFICEo GEORGE B. SCOTT, OF BROOKLYN, NEW YORK, ASSIGNOR TO EUGENE F. PHILLIPS, OF PROVIDENCE, RHODE ISLAND.

TELEPHONE-EXCHANGE SYSTEM AND APPARATUS.

SPECIFICATION forming part To all whom may concern:

Be it known that I, GEORGE B. SCOTT, of

l the city of Brooklyn, in the county of Kings nication as has heretofore been attained by the use of double wires, of which one is devoted exclusively to calling or'signaling purposes. I thereby obviate the cost of the expensivelyinsulated special wire and all that pertains essentially thereto in the way of line care.

Another object is to signal over asingle wire by direct telephonic communication between subscribers and central stations, thereby obviating the cost of annunciators at the central stations, the care and attention incident thereto, and more particularly obviating the delay and confusion incident to the operation of annunciators, involving, as they do, great nicety of adjustment, and being specially liable to temporary derangement and uncertain operation.

Another object is to enable the business at the central station to be conducted in silence by the operatives, thereby securing prompt attention to business and obviating the errors naturally incident to loud and hurried calling, and also to render it practicable tocarry out a reliable registry of service to each subscriber, so that each may be called upon to pay in proportion to his actual employment of the system, thus tending to unburden the system of much, that is trivial and reducing its operations to a practical business basis; also, to maintain betweeuthe subscriber and the central station a signaling and telephonic .com-

vmunication which is not dependent upon the manipulation of switches by subscribers, whereby I obviate the delays and inconveniencesv incident to switch-setting at the hands of careof Letters Batent No. 253,316, dated February 7, 1882. Application filed February 11, 1880.

less or inexperienced persons. This feature, so far as my knowledge extends, has never before been attained.

For the attainment of these ends my invention, broadly stated, consists of a telephonic exchange system embodying a series of independent subscribers wires or circuits, all branching out and normally in connection with a central receiving-instrument at the central office or station, but adapted to prevent the currents, ora 'sufticientportiou thereof, from being diverted into the branch circuits not in use, and provided with apparatus to receive and transmit signals at said central office or station; and, further, in a telephonic exchange system, a series of closed circuits centering in and passing through a single central instrument and resistance in the said circuits to confine the electric currents, or the main portions thereof, in the circuit passing through said central instrument; and, further, in a telephonic exchange system, a series ofcircuits, all unitingand passing through a single central instrument, and adapted to confine the main portion of the current tothe circuit passing through said central instrument, combined with electric switches adapted to be operated from the central office to close the distant end of the said circuit through a branch circuit or electrical connection to ground, to enable the usual signals to be operated from the central oflice; and, further, in the combination, with a series of wires, each communicating with one ormore subscribers and radiating from a ground-wire at the central station, of a listening-telephone connected with said ground-wire and a high resistance nearthe terminus of each subscribers wire.

The gist of the several features of invention thus far stated is in providing such a high resistance or its equivalent at the outer end of each subscribers circuit or wire that telephonic communication is assured between any one subscriber and the ground-wire telephone at the station, regardless of the central connection with the same ground-wire of the other subscribers wires.

For telephonic communication with the central station and between subscribers, an electric power of the ordinary character is only required--as, for instance, that involved with a Blake transmitter; but for operating each subscribers signal apparatus from the central station a higher electric power is necessary in order to overcome the high resistance on the subscribers wires; and for the reason that my system, as a novel feature, involves the employment of two distinct electric currents of different power I term it the duplex sys tem. The source of the high electric power may be derived from chemical batteries or from dynamo-electric apparatus; and in that connection my invention further consists of a series ofsnbscribers wires, a telephone, a high resistance, and a signaling apparatus at the terminus of each wire, and a central station having a ground-wire and listening-telephone common to all the wires, in combination with a battery or a dynamo-electric machine and suitable means for applying the electric power therefrom to any of the wires for overcoming the high resistances thereon and operating the calling-signal. In this combination it is to be understood that the telephone at each subscribers station necessarily involves some means whereby an operative electric current is aiforded for transmission of sound-vibrations to the central station, said current, however derived, being one of the two currents of different powers employed in my novel duplex system.

My invention further consists in a sub-combination as follows, viz: a series of wires for telephonic communication radiating from a central station, each connecting with a subscribels signal apparatus located between a high resistance and ground, in combination with means at the central station for obtaining an electric current of sufficient power to overcome said high resistance and means for applying said current to any and all of said wires for operating subscribers signals. In this last stated combinationI do not limit myself to any special telephonic system, for although it is of great importance in the particular novel system herein disclosed,Iam well aware of the value of the principle involved, and realize the practicability ofits application in other systems.

Under my present system more than one subscriber can be served through a single wire, in which case the high resistance is located with the terminal subscriber, and therefore all the signals on that wire will be sounded simultaneously, requiring each to determine as to his own particular cal], and causing the nearest subscriber, while using the line, to automatically cut off those beyond, and also exposing any of the outermost subscribers, when using the line, to interruptions from any subscribers between them and the central station. It is therefore of special importance that I obviate, as hereinafter described, all manipulation of switches.

Certain other minor features of invention will be hereinafter fully specified.

To more particularly describe my invention, I will refer to the accompanying drawings, in which-- Figure 1 represents the apparatus employed at a central station. Figs. 2 and 4 represent the apparatus employed at terminal subscribers stations. Fig. 3 represents the apparatus employed at an intermediate subscribers station. The several stations are shown with proper line-wire connections.

I will first describe the apparatus at the central station.

I employ, as heretofore, connecting'bars A,

proportioned to the number of subscribers to be served therewith and also to the extent of their business. As a rule, seven or eight sets of bars will be ample for fifty subscribers. Heretofore a single connecting-bar has been employed for receiving the plugs of two switch-cords, respectively connected with the switches of wires of two parties in communication. My connecting-bars are of a novel character, in that two separate bars electrically coupled together and to a battery constitute a set of connecting-bars. These pairs or sets of bars operate as one bar, so far as a relates to the mere connection of two switches; but they are also capable of being coupled to a battery for applying its electric power to the line over which communication is desired. As another novel feature in this connection, I employ an electric indicator, A, which is interposed between the bar-battery and the bars, whereby at a glance it may be determined whether the bars to which it belongs are in service. As will be hereinafter more fully shown, there is no high resistance on lines which are coupled and opened to telephonic communication via the central ofiice, and therefore the bar-battery has sufficient power to deflect the galvanometer A for showing that the lines which are coupled through the bars are occupied, and when thereafter those lines resume their normal condition, with the high resistances thereon, the bar-battery being incapable of suflieient circulation to longer hold the galvanometer-needle, it falls back to zero, indicating that telephonic service through that set of bars has terminated. This indicator A may be variously constructed; but a simple form of galvanometer will serve the purpose, its needle indicating promptly whether the barbattery is in open or closed circuit; and as an additional novel feature I employ a hand-indicator, A, which is to be pushed to one side when its particular set of bars is putinto service and to the opposite side when the serviceis terminated, affording positive information to the switchman as to disengaged bars, and rendering it obviously unnecessary to watch all the electric indicators. Each of these handindicators operates as a shield over the proper number of its connecting-bars when said bars are in use.

The several line-wires enter the station as heretofore, and of these but three are shown 10. by wire I), which extends through a listeningtelephone, D, and thence to ground. The keys a are normally out of circuit with battery a so that communication is always open over all the line wires through said keys,

thence through the switches, and thence to and through the listening-telephone to ground. On pressing either keythe full force of battery a is applied to its liuewire for signaling purposes, as hereinafter more fully explained.

The telephone-listener, being always in communication with all the subscribers wires, is ready to respond as directed in each case. I

The mode of connecting any two line-wires by meansofthe usual switch-cords, c, is effected by placing them in the switches and the connecting-bars,-thereby taking in the small battery, and the presence of a switch-cord plug cuts off communication of theline-wire to which the switch belongs with thelistening-telephone 0 at the central station.

1 will now proceed todescribe a terminal snbscribcrs station on one of the linefwires, illustrated fully in the drawings.

It will be remembered that all the line-wires atthe central station terminate in a groundwire tapped by a listening-telephone common to all the wires. ,As usual, the outer end of each linewire terminates at ground; but on entering a subscrihers station it connects with a spring switch-lever, E, provided with a hook at its end for carrying, as usual, the telephone F, which, by its weight, maintains said lever against its lower stop, d, from which the linewire is practically continued, as at d, to and through a high-resistance relay, G, thence through a signal-bell,H, and thence to ground. This relay G, as employed by me, constitutes an electric switch'adapted to be operated from the central oflice fonenabling the required callingsignals to be made from said office, whether there be one or more subscribers on any one wire or circuit. While I prefer to locate the high resistance on the line side of the hell, I

do not limit myself thereto because when in- 5 5 termediate stations are provided for, as hereinafter explained, said stations have no separate high resistances, but rely upon the resistance at the terminal station on the same circuit, and therefore insuch circuits the resist- 6'o ance is between the signal-bell of an intermediate station and the ground, instead of being on the line side of sa'idbell. The line-wire projection d. is connected oiropposite sides of the resistance by wirescl and an armature, e,whereby, when the full force of theheavy battery at the central station is applied to the line-wire,

the high resistance of the relay G-say of five thousand ohms-is so far overcome as to cause the movement of the armature e to its stop 6, thus providing a direct but slightly intermittent passage for the heavy battery-curren t, having ample power to work the bell according to the movement of the proper line-signal key at the central station,

The high-resistance relay may be constructed of very fine German-silver wire, and thus be neitheroverexpensivenorbulky. Thebellpreferred by us is one of the single-stroke variety.

The signal having been received, the telephoneis lifted from its hook, whereupon the switch-lever E is lifte y its spring from its lower stop, d, thus cutting off the ground-connect-ion via the line through the resistance G and opening up the requisite ground-connection, as follows:

The switch-lever E has on its upper surface a wedge-shaped spur, as commonly employed for operating with a double spring-stop,as shown atf, the opposite sides of which respectively connect with a Blake transmitter, I, (or other suitable apparatus and through it with the telephone F, and thence in the usual manner to ground m'a wire g, thus placingthe sub- -scriber in telephonic communication with the centralstation, and with the calling party when theproper switch-board connections have been made at the central office.

For calling the central station the subscriber has only tolift his telephone and speak through it or the transmitter, finding always a listener on duty at the central oflice. Itis during this calling of subscribers that the high'resistance performs its important functions. If, say, fifty wires are employed in one series, each with, say, five thousand ohms, the resistance to be overcome on anyone wire through the telephone when grounded at its outerend will not exceed about one' hundred ohms, and such a lowresistance does not impair the conversational capacities of the line. Were it not for these high resistances on each of these Wires, no practical results could be attainedas, for instance, when fifty wires are employed, all of them would be practically open to ground at their outer ends, and therefore free to be traversed by the telephone vibrations from any one telephone; but when thus guarded by the resistances, each wire serves practically the same purpose as if it were not one of a series of wires having a ground and a listening telephone commcn to all of them.

Although it is preferable to have a single subscriber for each wire, two or more can be located thereon with no disadvantages other than sueh'as areincident to other systems. The liability of simultaneous calls lrom two or more subscribers to the listening-telephone at the central station and the possibility of confusion incident thereto are presentin the special signal-wire system, and also in my system, whether each wire is or is not limited to one subscriber; but when Lplace more than one,

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IIO

subscriber on a wire no persons beyond the party using the line can contribute to this confusion, for they will be cut off from the central station so long as an intermediate one is in use. In calling from the central station all the signals on one wire will be sounded as heretofore under similar conditions, requiring special signals and attention thereto from each subscriber, whereas on a single-subscriber wire a sounding-signal of any kind is only required.

An intermediate subscribers apparatus is illustrated in Fig. 3. [t has no high resistance, that being required only at the terminal station. Its signal apparatus H occupies a position on the line via the spring-switch lever E, its lower stop, (1 and wire d thence to the outward line toward the terminal subscribers station. The telephone and transmitter are precisely the same as at terminal stations.

For cutting oh" the outer line and attaining a local ground-connection a thumb-switch may be employed; but as the careless failure to properly return the switch to its normal position would keep all subscribers beyond out of communication with the central office, I-have provided an automatic spring-switch, K,which is located abo e the outer end of the switchlever E, on which the telephone I is supported when not in use. This switch K is wired at h to wire g, leading from the telephone to the line-wire beyond, and its stop z" is wired direct to ground. The spring of switch K maintains it normally in a depressed position away from its stop, and it is lilted by the telephone switch-lever E, with which it has an insulated contact, so that when the telephone is taken from its book the telephone ground-connection is attained via wires g and it, through switch K and the ground-wire leading from stop 1'.

As a means for readily indicating to all subscribers the electric condition of a line-wire common to several subscribers, I apply at each subscribers apparatus an electric indicator of a simple character, similar to the indicators A employed at the central station.

The sub-combinations deemed by me to be novel in my apparatus are as follows: an electric signal-bell and ground-wire connection guarded on the line side of the bell with a high resistance; on a telephonic line-wire provided at its outer end with a high resistance and a calling-signal, a relay by which said high resistance is cut out for operating the signal; at an intermediate subscribers station on a telephonic line-wire provided at its outer end with a high resistance, a spring switchlever maintained in a depressed position by the weight of a telephone hung thereon, and a switch to ground, automatically controlled through they utomatic movement of the spring switch-lever when relieved from the telephone and when loaded therewith; in the centralstation apparatus, the combination, with each pair of connecting-bars, of an electric indicator for disclosing the termination of service, and also a hand-indicator mounted on'or near the connecting-bar board, and arranged with relation to its particular set of connecting-bars so as to be under the eye of the switchman while on duty.

In describing the operation of the system as a whole 1 will refer to the drawings as a whole, wherein are illustrated a central station and two terminal and one intermediate subscribers stations, all clearly designated. It will be assumed that there are at the central station one or more series ofline-wiressay fifty in eachand that all the switch-boards'are capable of switch-cord connection for placing the subscribers ofany one series of wires in com munication with those of the same or any other series. For each series a listening operator at its telephone D is required. A switchman can ordinarily attend to the switch-boards of more than one series. An observer to watch the galvanometers A sets the hand-indicators A and conducts the preliminary operations for attaining a registration of service, both as regards time and number of calls. Thennmber ot'switchmen and observers at a central station may therefore be graded by experience according to the extent of its business. In some cases the observer and switchman may be combined in one person. For conducting the business in silence a set of blanks is required. One bearing the words Connect it it with it another Disconnect bars No. It a time grade of service is desired, both should have, in addition, Bars No. and Time printed thereon. For the best results as to dispatch and convenience, subscribers should call by their predetermined number, although their names may be used instead. \Vith the listening operator at telephone D, the switchman in front of his switch-board, and the observer within reaching distance, a subscriber at either station lifts his telephone from the hook on the switch-Fever and calls direct: Connect 25 with 50. The listening operator writes those numbers on a blank for that purpose, or names if they be used, and hands it to the switchman, who then taps the key a, which communicates with 50 a sutlicient number of times to insure a response if he is available, and then with a switch-cord couples the 25 and 50 wires via their switches and any one of the unoccupied pairs of connecting-bars A, the galvano-indicator of those bars showing whether response is being made, and, if not, further taps on the key will bein order. If 50, on being called, lit'ts his telephone from its book, he finds himself in direct telephonic communication with the party (25) who called him. The observer, on noting the position of the galvanoindicator, then moves the hand-indicator to the one side, disclosing the number .of the set of bars in service, showing the switchman at a glance which bars are open for use or are occupied. The switchman having handed the blank to which response has been made to the IIO observer, he notes thereon thctinie of day and nals to be operated on any of the circuits from places the blank on a spindle-file. When the the central office;

galvano-indicator shows termination of service, the observer writes into a blank Disconnectbars No.1, which is handed to the switchman. The hand-indicator is then set back to cover its number, showing that said bars are again open for use. i The switchman places said disconnect blank on a spindle-file, first noting time thereon, ifdesired,and so on,without requiring a word for conducting the business. Should the listening operator require to orally communicate with parties calling-as, for instance to respond O. K, on receiving a call, or for stating that No. 50 does not connectit would constitute the only talking requisite at the central station, and the absence of loud calling and other conversation enables the listener to more accurately perform his duties. On the relief of each set'of operatives the blanks are reversed in position on the files and handled singly for registration either by assorting them for preservation or by special entry for each days service. Should any two or more subscribers simultaneously call, the listener has only to call out: One at a time, Goon, 50, or such number as he has been able to fully catch, and so on until all are disposed of. The connections between two or more central stations and their respective subscribers can readily be effected by means of a series of stationwires, each wire being numbered, so that by telephone order may be given from either central station for connection at any other of a subscribers wire of a certain number with a specified station-wire, which is then connected with the calling party via the connectingbars A.

Having thus described my invention, Iclaim as newand desire to secure by Letters Patent- 1. In a telephonic exchange system, aseries ofiud ependent subscribers wires or circuits, all branching out from and normally in connection with a receiving-instrument at a central office, but adapted to prevent the currents, or a too great portion thereof, from being diverted from the circuit through said central instrument into the branch circuits not in use, and provided with apparatus to receive and enable signals to be made from said central office.

2. In a telephonic exchange system, a series of closed circuits centering in and passing through a single central instrument, and resistance in the said circuits,to confine the electric currents, or the main portion thereof, in the circuit passingthrough said centralinstrument.

3. In a telephonic exchange system, a series-- of circuits, all uniting and passing through a single central instrument and adapted to confine the main portion of the current to the circuit passing through the central instrument, combined with electric switches adapted to be operated from the central office to close the distant end of said circuit through a suitable connection to ground, to enable the usual sig- 4; The combination, substantially as hereinbefore described, of a series of wires for telephonic communication with one or more subscribers on each, and 'radiatin g from a single ground-wire at a central station, with a listening-telephone connected with said ground-wire and a high resistance near the outerterminus of each subscribers wire.

5. A telephonic exchange system embodying, substantially as hereinbefore described, a series of subscribers wires, a telephone, a high resistance, and a signaling apparatus at the outer terminus of each wire, and a central station having a ground-wire and a' listening telephone common to all of the subscribers wires, in combination with a suitable battery or its equivalent and means for applying the electric power thereof to any and all of the subscribers wires for overcoming the high resistances-thereon and operating the calling-signal.

6-. The combination, substantially as hereinbefore described, of a seriesof telephonic subscribers wires radiating from a central station, and provided in each case with a subscribers calling apparatus located near the outer terminus of the wire and between-a high resistance and ground, with means at the central station for attaining an electric power to overcome said high resistances and means for applying said power to any and all of the wires in the series for operating subscribers signals.

7. In a telephonic exchange system involving a series of subscribers wires or circuits branching from a ground-wire common to all the subscribers wires, a high resistance located near the end of each subscribers wire, as and for thepurposes specified.

8. In a telephonic exchange system involving a series of subscribers wires or circuits branching from a ground-wire common to all of them, a calling-signal near the outer end of each subscribers wire, a high resistance, and a relay operating as a switch for cutting out said resistance, as and for the purposes specified.

9. ()n a telephonic line-wire provided at its outer terminus with a high resistance, the combination of a spring switch-lever maintained in a depressed position by the weight of a telephone thereon,and a switch to ground, which is automatically controlled by the switch spring-lever when loaded with or released from the weight'of the telephone, substantially as described.

10. At a central station in a telephonic exchange system, the connecting-bars, constructed in pairs, coupled together and to a battery, substantially as described,whereby the power of said battery is placed on any twosubscrib- IIO ers wires when coupled by the connectingwith means-such as connecting-bars and conducting-cords-for connecting subscribers lines with each other, so that in connecting said lines by the aforesaid means the electric indicator and battery are included in the circuit, as set forth.

12. The combination, with subscriberslines having each a high resistance at the end and a telephone-switch of ordinary or suitable construction for cutting out the said resistance and connecting in the telephone, of a battery, an electric indicator, and means-such as conmeeting-bars and conducting-cords-for connecting subscribers lines, said indicator and battery being connected with the said means, as indicated, so that when the subscribers lines GEO. B. SCOTT.

Witnesses:

B. M. VREELAND, RALPH W. Porn.

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