US1247395A

US1247395A - Automatic telephone system.

Info

Publication number: US1247395A
Application number: US37184307A
Authority: US
Inventors: Charles L Goodrum
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1907-05-04
Filing date: 1907-05-04
Publication date: 1917-11-20
Anticipated expiration: 1934-11-20

Description

. c. L. GOODRUM. Aurommc TELEPHONE svsnzm. APPLICATION FILED MAY 4; I901. Patented Nov. 20, 1917.

8 SHEETSSHEET l- C. L. GOODRUM. AUTOMATIC IELEPHONE SYSTEM. APPLICATION FILED MAY 4. 1907.

Patented Nov. 20, 1917.

8 SHEETS-SHEET 2.

Qvwentoz Wifnwou C. L. GOODRUM. AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED MAY 4. I901- 1,24:7,395. V Patented Nov. 20, 1917.

8 SHEETS-SHEET 3- warmma W aka/0% C. L. GOODRUM. AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED MAYMIBO]. 1 247,395. Patented Nov. 20, 1917.

GZJMK I lvil'ueoaeo Q u v C. L. GOODRUM. AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED MAY 4.1907- 1,247,395.

Patented Nov, 20, 1917.

B SHEETSSHEET 5.

N I Jwumtoz C. L. GOODRUM. AUTOMATIC TELEPHONE SYSTEM. APPLICATION FILED MAY 4, 1901.

Patented Nov; 20, 1917.

8 SHEETS SHEET 6.

"Q/vi In macs 3 &

. WI hwaoeo c. L. eoonaum; AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED IAY 4, I907. 1,247,395. I

Patented Nov. 20,1917. I

3 SHEETS-SHEET I.

b'oA

slmmnfoz W fly/MA m CHARLES L. eoonnou,

OF ROCHESTER, NEW YORK, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OF NEW YORK.

Specification 0! Letters Patent.

AUTOMATIC TELEPHONE SYSTEM.

Patented Nov. 20, 1917.

Application filed May 4, 1907. Serial No. 371,843.

To all whom it may concern:

Be-it known that 1, CHARLES L. GOODRUM, of Rochester, in the county of Monroe and State of New York, have invented certain new andusefiil Improvements in Automatic Telephone Systems; and I do hereby declare the following to be a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming a part of the specification, and to the reference-numerals marked thereon.

My present invention relates to automatic telephone systems, and it has for its primary object to provide an improved system in which the talking and signaling operations between different subscribers stations, and the apparatus for connectin difi'erent telephone lines, at the central 0 ice or exchange, may all be effected over a full metallic circuit comprising but two wires without grounded connections.

Another object of the invention is to provide means for connecting different telephone lines at the central ofiice or exchange comprising generally a finder switch and an associate connectorswitch, both serving a plurality of lines, the former operating automatically to select a line on which a call originates and extend it to the connector switch which latter is responsive to'impulses of current on the calling line and serves to connect it to a particular outgoing line on which it is desired to call a subscriber, the signaling of said called subscriber being accomplished automatically.

In addition to the above described attainments of the invention it also comprehends the employment of two or more finder switches, the movable elements of which travel in opposite directions, or move in the same direction to cocperate'with equivalent setsof line or instrument circuit terminals, arranged in reverse positions in the banks of contacts on the two switches, whereby one of them will pick up the incoming line in advance of the other. The arrangement of these parts of the apparatus has this additional function; that should the first switch fail to make the connection, the line will be subsequently picked *up by the second finder switch, when its movable elements engage its respective terminals of said line.

The arrangement of the parts of the apparatus embodying this invention permits another object to be obtained; namely; the location of an incandescent lamp at each subscribers instrument which is lighted by current in the instrument circuit supplied from the central otfice or exchange, when said circuit is closed. The lighting of this lamp as soon as a subscriber removes his receiver,

illuminates the dial of the impulse transmitter and facilitates the subscriberslabor in sending in a call.

To these and other ends the invention consists in certain improvements and combinations of parts all as will be hereinafter fully described, the novel. features being pointed out in the claims at the end of the specification.

In the drawings:

Figures 1 and 2 are illustrating generically the line connection as it is effected between two instrument circuits by means of the finder and connector switches, the operating mechanism of the switches being omitted, the first view showing the positions of the switches in connecting instrument A with instrument B and the second illustrating the reverse connection.

Fig. 3 is a plan view illustrating a type of switch .which may be employed as finder and connector switches for operation with this system.

Figs. 4 and 5 are detail sectional views thereof taken on the lines P -4:" and 5"-5 respectively.

.Fig. 6 is a diagrammatic view illustrating a finder switch in conjunction with an, in

diagrammatic views strument circuit, including that part of the switch controlling mechanism which automatically extends said circuit to the connector switch, and p Fig. 7 is a similar view of the connector switch showing the controlling mechanism by means of which the switch connects an incoming line or circuit, on which a call is originated, to another outgoing line.

Fig. 8 is an enlarged diagrammatic detail view of the devices for operating the con- ,description,

hector switch illustrating the operation of the mechanism for setting up a connection and subsequently restoring the switch to its normal position.

Fig. 9 is a diagrammatic illustration of the apparatus associated with that shown in Figs. 7 and 8 for automatically operating the callingdevices on the various outgoing lines or c1rcuits intermittently which is arrested when the called subscriber answers his signal.

Fig. 10 is a diagrammatic view showing duphcate arrangement of the assocated finder and connector switches shown in Figs. 6 and 7.

Similar reference numerals in the several figures indicate similar parts.

In a telephone exchange. system embodyin my invention the connections between difierent telephone lines are automatically set up or-efl'ected by apparatus arranged at the central office or exchange, and the telephone lines or circuits are divided into two classes comprising, first, incoming lines or those on which calls are ori inated, by sub scribers who desire toesta cation with other parties, and, secondly, outgoing lines over which the calls are'despatched to signal said parties. Each line may, at different times, be of either class and it will therefore be understood when these lines are referred to in the following that an incoming line or circuit is one leading from a subscribers telephone or station over which impulses of current are sent to connect said line to an outgoing line and that the latter is the oneon which the signaling devices are actuated when the connection has been set up or completed between the telephone instruments of the callin and the called subscribers.

n the system embodying the present invention it is possible to connect through the central oflice or exchange apparatus a given line with any other line and to this end all the lines lead to terminals on a finder switch, or a pluralit of such switches, and to simi lar termina s on an associate connector switch or switches. The finder switch -performs the function of selecting an incoming line on which a call has been originated, and the connector switch performs a similar function in selecting the outgoing line leadin to a particular telephone instrument or sufiscribers station, with which the calling subscriber desires to communicate. The movable elements or wipers of the finder and connector switches are connected, or tied together, so that when the functions of each have been performed, the talking circuit, from the incoming to the outgoing line, is extended throu h them and ma be retained until one of t e twocommumcating subscribers desires to effect the discon- 66 nection of said lines.

lish communir In Figs, ,1 and 2 the above described connections are shown diagrammatically, two separate instruments being shown in each, and indicated generally'by A and B, with a singlefinder switch F and a single connector switchC. In Fig. 1, the movable elements or wipers of the two switches are shown in position to illustrate the connection established from'instrument A to instrument B when the circuit of the first mentioned instrument is the incoming line on which a call is originated, and In Fig. 2 these parts of the switches are shown in the position which they occupy when instrument B is the one on which a call was initiated. I

The telephone instruments may be of the usual or any preferred construction comprising generally a transmitter 1, a receiver 2, and the signaling devices or bells 3, all of which are arranged in the circuit of the line wires AA of instrument A, and B'B of instrument B. The instrument circuits are normally open at each subscribers station at the contacts A B which are controlled by the receiver hook and are closed when thelatter is released by the subscriber removing his receiver therefrom. Each pair of wires constituting the circuits ofthe telephone instruments is extended to the aforementioned switches located at the central oflice and terminate in immutable contacts located thereon, those of the wires AA being located on the switch F, as indicated by A the corresponding contacts on the switch C being indicated by A -A said contacts being tied. together by conductors A -A the similar contacts of the wires BB- on the switch F are indicated by B"" and onthe switch C by B -B said pairs ofcontacts being also tied together by wires B The operating mechanisms controlling the movable elements or wipers of the two switches have been omitted from these illustrations but as will appear more fully hereinafter, they are designed to cause such switches to move progressively over a bank of contacts or terminals, representing a large number of telephone lines. The wipers of the switch F are indicated by F-F and those of the switch C by C-C the corresponding wipers of thetwo switches being connected by 1

wires

4 and 5. From an inspection of Fig. 1 it will be seen that the complete circuit between the instruments A and B is traced as follows:- instrument A wire A, contact A ,;wiper F, wire 5, wiper C contactgB", wlre B, instrument B, wire B contact B wiper C, wire 4, wiper F, contact A, wire A, instrument A. The foregoing, is predicated upon the fact that the call originated at the instrument A and the mechanism of the finder switch operated to pick u the contacts of the incoming cirthe switch C. These elements arearranged one below the other and their outer endsare ment B.

Supposing a reverse operation to be ef-,

The movable ,ele

fected in a like manner. ments of the finder switch F first traverses its bank ofcontacts or terminals, until reachthe terminals -B then. the connector switch C operates to pick up the terminals A -15. of-

The circuit between the the line AA two telephone instruments will then be traced as follows: instru'mentB, wires B B contact B wiper F, wire 4, wiper C, contact A, wires A, A instrument A, wiresA, A", contact A, wiper C, wire 5, wiper F3, contact B,'wires B", B, instru- T he switches.

In illustrating the mechanism by means of which the connections between the lines is efl'ected,'a type of switch adapted for this urpose is shown in Fig. 3, details thereof eing shown in Figs. 4 and 5. Thisfswitch is capable of performing the functions of either the finder or connector switch, and comprises generally a progressively movable member 6, which is adapted to be advanced step-by step, and to thisend is made circular in form and is mounted upon a revoluble shaft 7 journaled at its lower'end in the base plate 8, and supported at its upper'end by a bearing on a bracket 9, the" ends of which extend downwardly and are secured to the base plate, as shown in Fig. 5. Carried on the movable member and insulated therefrom are contact, elements or spring wipers 10 and' 11, corresponding to the wipers F'-F of the switch F and C'-C of adapted to coiipe'rate with a series of insulated terminal contacts 12 and 13, arranged in pairs corresponding to the contacts.

A etc., those of each pair being lo cated in vertical alinement as shown in Flg.

4. As each switch controls a plurality of telephone lines, these pairs of terminals are supported upon a segmental bridge 14, and are arranged concentric with the center of movement of the wipers. Beneath said contacts are

other contacts

15 and 16 with which of the line.

the shaft 7 a coil spring 20 to which suflicient tension is applied to return the shaft and the parts supported thereon to the normal position, shown in Fig. 3, when they are released. 1

The 'means for operating the movable element comprises a pawl 21', pivoted to the upper end of an arm 22 on which it is moved by a. spring 23 into engagement with teeth 24 on the periphery of the element 6. The arm 22 is pivoted at the point 25 and is provided with a laterally extending end 26, forming an armature which coiiperates with the-motor magnet 27, employed for actuating the, operating devices, said armature be-- ingnormally held in retracted position by the spring 28 bearing against the stud 29 on the arm 22, which also serves to advance" the member 6 when the pawl 21 is in engagement therewith. A spring operated pawl 30 serves to lock the movable element in adjusted position and at its outer end is a fin-' ger 31, projecting beneath ,theend of the pawl 21, the arrangement of the parts being such that when the pawl is moved down-' wardly into an inoperative position the .detent will be retracted, as shown in Fig. 3. The means for effecting the release of the member 6 comprises'a spring latch member 33 having an end 34 which is adapted to hook over the edge of a lip 32 depending from the pawl 21. At its lower end the spring, 33 is attached to an armature 35 pivotally supported in proximity to the release magnet 36 and carrying an upwardly extending arm 37 provided with a stud 38 with which cotiperates a spring 39 normally tending to move it in a direction to retract the armature '35. Supported uponthe base plate 8 in front of the spring 33, is a stud 40, whlch llmlts the lateral movement of the springwhen the armature 35 is retracted,

thereby permitting the lip 32, of the pawl to be disengaged from the hooked end of the spring when said pawl has been re-, tracted by the energizing of the motor magnet 27 The movable member, 6, controls two circuits, as will be further described in connection" with the diagrammatic illustrations, which include a contact spring 41 playing between

contact members

42 and 43, supported in a holder 44, on the base plate 8. The spring 41 has a normal tendency to engage the contact 42, but is heldin engagement with the contact 43, when the member 6 and the contact elements carried thereon are in their normal position, by-a pin 45 mounted on the member, which releases said spring upon the first step or movement imparted thereto.

The finder and connector switches are actuated by electromagnetic devices peculiar to each, those ofthe finder switch being antomatically set into operation, and controlled by secondary circuits, which are established when an instrument circuit is closed at the subscribers station, and the mechanism of the connector switch is rendered operative when the finder switch has picked up the incoming or calling circuit and is controlled by impulses of current which may be despatched by a suitable form of impulse transmitter located at the subscribers station, to select a given outgoing line, or called circuit. Accordinglythe instrument circuit, comprising wires AA is extended, as indicated at A Figs. 1, 2 and 6, to normally closed contacts AA, one of which is mounted upon a spring finger provided with an end 46 adapted to cooperate with teeth of an impulse transmitter A which may be rotated to separate said contacts and thereby transmit or send over the operating circuit one or more impulses of current, when the circuit is closed at the hook contacts A The electromagnetic mechanisms for causing the various switches to perform their respective functions, are all adapted to be operated from a common battery Z, Figs. 7 and 8, but in order to facilitate the description and illustration, and render a more comprehensive understanding of the variouscircuits to be had, these are shown in the diagrammatic views as receiving current from diiferent sources or sets of batteries,

ZZ etc. The circuits in many instances, are shown with the conventional ground or earth connections, but it will be understood that where the term ground is employed and shown, it refers to a connection leading directly to one side of the main battery, so that a telephone system embodying this invention, when installed in working order, is entirely free of the so called grounds employed for actuating parts of the apparatus, thereby eliminating line disturbances or other troubles attributable to this cause.

The finder switch.

Associated with each telephone line or instrument circuit, is an actuating relay A, which is energized when the instrument circuit is closed to actuate the operating mechanism of the finder switch F, and a cut-oflf relay A, the function of which is to restore the actuating relay to normal position when the finder switch has picked up its corresponding instrument circuit. In Fig. 6 the finder switch is shown provided with a plurality of sets of the four terminal contacts which are arranged in rows, as illustrated in Fig. 4, those constituting the lower pair of the set related to the circuit of instrument A. being indicated by ff Leading from the contact f is'a wire A connected to one end of the'coil of the cut-off relay A, the other terminal thereof being supplied at certain times with current from the battery Z; another wire A leads from the contact "f2 -to a back contact a, with which the ed by a wire a which is joined to the other wire A" of the instrument circuit, This armature normally engages a backcontact a which; has a grounded connection; .2 In Fig. 7 corresponding parts to those just described arefound illustrated in connection with the instrument B, said parts being indicated by the use of the letters B, b, with the appropriate exponents, reference to which will be made hereafter in explaining the operation of certain parts of the apparatus.

It has been explained, in connection with Figs. 3, i and 5, how the movable contact elements cooperate with the several terminals in the bank of contacts of each switch, but in Figs. 6 and 7 the illustrations are simplified by showing the circuit wires connected directly to the wipers, whereas, in reality they are connected to brushes, such as 10", 11, 17 18', shown in Fig. 5. Referring now particularly to Fig. 6, it will be seen that the brushes FF are extended by the wires 4* and 5 through normally closed contacts on the armatures of two relays F F which will be described more fully hereinafter, the function ascribed to the former being that of opening the extended instrument circuit over the

Wires

4 and 5, during the rotation of the brushes of the finder switch F, when moving in one direction to pick up an incoming line, while that ofthe latter relay is to open said circuit during the movement of these parts when returning in the opposite direction to their normal position. The opening of the ties between the switches eliminates any vibration in the receiver of a subscribers telephone when a plurality of switches are employed for the purpose of handling two or more incoming calls simultaneously, and it also prevents any possible interference with the connector switch mechanism during the retrograde movement of the parts of the finder switch.

Operating conjointly with the motor and release magnets, 27 and 36 respectively, is a relay F which performs dual functions, namely: the completing of a secondary circuit of the motor magnet 27, over which current is supplied to cause its continuous operation until the wipers of the switch F have picked up the incoming line, and to close another circuit by means of which the cut-off relay A of said line is energized when its terminals have been found by the finder switch. The motor magnet 27*, the relay F and the line opening relay F are connected in parallel by the wires f-f but as the relay F will he referred to more fully hereinafter, it may be disregarded at this point and the wire f considered as grounded or connected to one terminal of the battery Z which supplies current to the starting circuit controlled by the armature a of the actuating relay A, Connected to one end of the coil of the motor magnet 27* is the batteryZ, the other end of said coil bein connected by the wire f to the armature f of themotor magnet, which normally enfined to the gages the back contact f of the wire f. The latter is also joined to the contact 7? with which the spring controlled switch arm f normally engages, the latter being connected by the wire f to the front contact f which is engaged by the ar'matureaa when the latter is attracted by the actuating relay A The other contact'with which the switch arm f cooperates, is indicated by 7 3, and this has a ground connection, 2 over which current is transmitted at certain times to permit the finder switch to be restored. The

third wiper, f" is connected by the wire 8 to an armature f on the relay F normalfy resting against a back contact f which is connected by the wire f, to a round a), over which current may be received from the battery Zto energize the cut-off relay A, when the brush f" engages the contact f. The fourth brush f is connected by the wire f" to an armature f, adapted to normally cooperate with a back contact f connected .by a wire f to ground. This armature, i is also arranged on the relay F and when the latter is energized 1t 1s moved into engagement with the contact f connected by the wire f= to the wire f.

The foregoing description has been conarts of a single telephone circuit but itwlll be understood that the finder switch F serves a comparatively large number of such circuits, each of which has associated with it the previously described actuating and cut-01f relays. The l1ne wires A, A and the local wires A and A of the several telephone circuits, are connected to the respective terminals of each her in the bank of contacts (such as those indicated by 12, 13, 15 and 16 i1; Fig. '4.)

All of the instrument circuits when not in use, are normally open at the recelver hook contacts A, and as the brushes of the finder switch, under such condition, are 1n inoperative condition, the spring sw tch f 1s retained in engagement with lts back contact I". In order to facilitate an understandmg of the movement of the finder switch, an addit onal telephone instrument has been: illustrated in Fig. 6; which is indicated by D. This subscribers set comprises the actuat 1ng relay D operating'the armature d, which is grounded at a and cotiperates with the back contact d connected by the local wire D to the terminal (1 on the SWIFCh F. The cut-off relay of this set is indlcated by- D, the circuit of which includes the wire D leading to the contact (Z on the switch F.. In the illustrations the terminals (Z and al of the instrument set D are purposely located in front of the terminals f and f with reference to the direction of rotation of the wipers of the finder switch, in order to facilitate the description of the circuits which are successively established by the movement of the switch.

Automatic operation of the finder switch.

When the subscriber at station A removes his receiver and closes the hook contacts'A the following circuitis established: instrument A, wires A a armature a, contact a wire a, relay A, battery 2'', by ground to Z contact a", armature a, wires a and A back to A. The energizing of the actuating relay attracts the armature, afl'completing the following circuit: ground a armature a contact f, wire 7', spring f, contact f, wire f, contact f, armature f wire f motor magnet 27*, battery Z to ound. The foregoing is termed the startmg circuit and that part extending from the con tact f is common to every instrument cir- Y cuit leading to the finder switch and coiip 'erates with the several branches connected to the spring f anyone of which may be closed by its respective actuating relay, to primarily actuate the motor magnet, when the switching of current causes the movable member of the switch to be advanced one step,,permitting the spring switch f to disengage the contact f and the four wipers to engage the first tier of contacts of an incomlng line, for instance those of the line D, but as the relay F was also energized, the armatures f and f thereon were attracted, the latter completing the following circuit: battery Z, magnet 27, wire f armature f contact f wires f, f" contact f, armature spective instrument circuits.

wire 7 brush f contact al wire D contact (i 9 armature cl, to ground .2

It should be stated at this point that the core of the relay F 5 is provided with a copper jacket, or otherwise constructed, to render its operation sluggish, so that the armatures f and f are'not released the moment the armature f is attracted by the motor magnet 27%. For this reason it will be seen that the dlflerence in the time constants of this magnet and its associate relay permitsthe switch brushes-traverse the bank of con tacts, and step from one set of terminals to another. As both of these circuits are completed through the brush or wiper f they are common to all of the instrument circuits connected to the finder switch and the local wires such as A, D, constitute branches of said circuits which are controlled by the actuating relays of the re- All of the o crating circuit branches are normally closed or connected to one side of the battery when the actuating relays are denergized; while the starting circuit branches are all opened. Consequently the energizing of a line relay reverses the condition of the branches. under its control, namely, it closes the starting circuit and opens the operating circuit. It will therefore be seen that each time the wiper f passes onto a contact, grounded as at a, an additional impulse of current is given to the motor magnet of the switch and the onward movement of its wipers will continue until the wiper 7 reaches a terminal of the operating holding circuit branch belonging to the incoming line on which the call was originated as said circuit branch will then be open at the actuating relay armature. This is shown in Fig. 6 in which the armature a is held out of engagement with the contact a by the actuating relay A which was energized when the circuit of instrument. A, the calling line, was closed.

The cessation in the flowof current in the circuits in the motor magnet, 27 and the relay F permits the armatures on the latter to restore or drop back to their normal position thus permanently breaking the operating circuit at the contact f At this time the brush or contact element f" is in engagement with the terminal 1' and the following circuit is established:

Battery Z, cut ofi' relay A, wire A contact f brush f wire f armature f conrelay A. As the Wipers FF are at this time in engagement with the contacts A A, respectively, the telephone circuit is then extended onward to the connector switch. J

Restoring the finder "switch to normal. The restoring of the finder switch F occurs when the instrument circuit which is closed in the first instance to actuate it, is

subsequently opened, as occurs when the calling subscriber hangs up his receiver and opens the hook contacts A The releasing magnet 36 is arranged in acircuit which includes the corresponding magnet of the connector switch C, which may be traced on Figs. 6 and 7 of the drawings. In order to simplify the description at this point, a temporary circuit has been indicated in Fig. 6 by the dot and dash line, although the full release operation cannot be stated except in connection with the connector switch C, as there are contacts in the truecircuit of the release magnet 36*" which are opened when the telephone instrument circuit is extended by the finder switch. The battery supplying current to the release magnet 36 is indicated by Z and between it and said magnet is a current interrupter Ff, which in the present illustration is shown as a rotary element adapted to be driven continuously by any suitable source 'by a circuit wire, f, as shown by the dot and dash lines, joined to the armature f arranged on the controlling relay F which attracts the armature away from its back contact, f connected by a wire f with the spring switch arm f. As'before men tioned, the contact 7' is connected to the ground 2", which forms the other terminal of'the battery Z It will be remembered that, during the rotation of the movable elements of the switch F, the controlling relay F is energized, consequently the circuit of the release magnet is broken by the armature f despite the fact that the other opening in said circuit is closed by the spring switch arm f, upon the first movement of the switching mechanism. The circuit of ground 2 the release magnet 36, may be traced as follows; when the switching mechanism ceases operation: battery Z brush i current interrupter F brush f, wire f, magnet 36* wire f, armature f contact f wire f", spring switch f, cont-act f, to The energizing of therelease magnet causes the movement of its armature and the retraction of the detent and pawl (parts 30 and 21, shown in Fig. 3), permitting the movable element to be returned to its normal position by the coil spring 20 (shown in Figs. 4 and 5.) 'The last described circuit is opened at the connector switch C before the slow operating relay F releases its several armatures, as

will be more fully described hereinafter, so,

that the temporary circuit wire f may be disregarded. I

The connector switch.

The connector switch comprises appara-' C'-C to permit theiradjustment into engagement with the terminal contacts of any instrument circuit on said switch and fur-- ther, to render the circuit so connected (the outgoing called line)'engaged or busy to prevent the called subscriber from attemptmg to set up a different connection through ThlS the switches F and C, at this time. mechanism is illustrated in detail in Fig. 7, and it is also shown upon a larger scale in F i 8. ssociated with the connector switch is the signaling and answering mechanism, the operation of which is effected by virtue of the aforementioned controlling devices, but as the circuits which are established for performing the functions of signaling and answering are not completed until after the controlling devices have performed their operations, this mechanism 15 illustrated separately in Fig.- 10.

Among those persons versed in this art it is customary to designate the two conductors of a telephone circuit, (such as A, A,) as the line and mate wires, and as these expressions will serve to elucidate further description, this nomenclature will be adopted. I

In tracing the circuit from the switch F to the switch C, it will be seen that the line and'mate wires P and 5, leading from the brushes, F'-F (in Fig. 6) are extended as indicated by P -5 (in Fig. 7)

V to the wipers CC of the switch C, and

have interposed therein condensers 47 and 48 and are supplied with current from the battery-Z by

wires

49 and 50 leading to the line and mate respectively. Inter-posed in the battery wires, 49 and 50 are line balancing coils 4 5 the latter being also used as a relay for performing one of the steps in establishing the signaling circuit. The line and mate conductors, 4 5, form the tie between the finder and connector switches and leading from these conductors are

branches

40 and 50, which are com nected, respectively, .to one end of the coil of the line relay 41 and the coil of the mate relay 51 The other end of the coil of the first mentioned. relay is connected by the wire 4" to a battery Z and the corresponding extremity of the other coil is connected by a wire 5 to a ground 2, corresponding to said battery, whereby, a current impulse therefrom will cause both the line and mate relays to be energized when the brushes FF of the finder switch F are in cooperative engagement with the terminals of theincoming lines These two relays are associated with the motor magnet 27 and the release magnet 36, of the C switch, and together they-control these magnets in the performance of their respectix e functions. These relays also have a time relationship, the mate. relay being preferably the one which .is so constructed as to have a more sluggishor retarded action than the line scribers station, and to destroy said circuit.

to prevent the operation of the motor magnet and render it inoperative to other current impulses subsequently transmitted over said circuit. The line relay 41 controls an armature 0 connected to one end of the coil of the motor magnet 27 by thewire c and cooperating with a back contact, 0 connected by the wire 0 with an armature '0, 9n the mate relay 51*, which attracts it into engagement with a forward contact 0" connected to the battery Z by the wire a. The other end of the motor magnet coil is attached to the wire 0 which has a ground loo . relay, so that its armatures will be held in attracted position during the vibration ofa over which current impulses from the battery Z are received. It will be seen therefore that current in the line and mate wires simultaneously energizes the two relays, the line relay opening the circuit of the motor magnet by attracting the arma-' mm 0 at the instant the mate relay attracts the armature 0 preventing the energizing of the motor magnet until the armature 0 is released.

The complete circuit of the line and mate relays can be traced as follows: Fig. 7, battery Z, wire 4* line relay 41*, wires 40 4*, Fig. 6, wire 4, brush F contact A, wire A instrument A, wire A, contact A,

brush F Wires

5, 5, (Fig. 7) 50 mate rel'ay 51, wire 5, to ground a. The operator at subscribers station A now despatches the de sired number of impulses over the aforedescribed circuit, to actuate the connector switch, and cause itswipers, CC to move into engagement with the terminal contacts of the outgoing line circuit, on which he desires to call a certain party, by opening and closing the circuit delineated above, the requisite number of times with sufficient rapidity to release the armature c and to continue its vibration to successively close and open the circuit of the motor magnet 27.

To illustrate this selective operation succinctly, let it be considered that the called subscribers station, heretofore referred to as B, is the instrument of which the line and mate wires are connected with the set of contacts designated by the numeral 400 in Fig. 3, which is the fortieth set of contacts in the bank of contacts of the connector switch, necessitating forty steps of the movable contact elements or brushes before the latter can engage them. The impulse transmitter, A will, therefore, be operated to open and close the contacts A and A, forty times; each impulse of current over the incoming line and mate wires (A' A 5 will energize both the line and mate relays, ell--59, but as the latter has a slow or retarded action, it does not release the armature c, and the latter is, therefore, held in engagement with the contact of during the vibration of the armature c which is attracted and released each time the incoming circuit is closed and opened. Conse quently a series of impulses in unison with' those transmitted over the incoming circuit b the successive opening and closing of t e contacts A and A, at station A, are transmitted over the motor magnet circuit, which may be traced as vfollows: battery Z, wire 0, contact 0, armature 0", wire 0 contact 0 armature 0, wire a, magnet 27 wire 0", to ground Z Upon the cessation of these impulses the brushes oi the connector switch stand in the posit1on sho wn in dotted lines in Fig. 3. In considering F ig. 7 further, the brushes C'C will be contact 0 to ground, 2

borne in mind as engaging the contacts B and .B.

Rendering a called line engaged or busy.

which leads the wire 0 terminating in an armature a arrangedon the local relay C,

and cooperating with a back contact, 0

connected to a ground a over which current impulses are received from the battery Z connected with the coil of the cut-off relay B, and supplying current to the following circuit: battery Z relay B, wire B contact 0, brush 0, wire 0 armature c, The foregoing circuit energizes the cut-off relay of the outgoing called line to prevent the called subscriber from disturbing the finder switch when he answers the call and closes his line through the hook contacts B The complete talking circuit from instrument A, the calling line, to instrument B, the called line, may now be traced as "follows: Fig. 7,

condenser 47, wire 4', (Fig. 6) wire 4, brush F, contact A, wire A, instrument A, contact A, brush F wire 5, (Fig. 7) wire 5', condensen 48, brush C contact B wire B, instrument B; wire B contact B brush C, wire 4. Current is supplied for part of the talking circuitfrom the battery to the two

conductors

4 and 5 by the

wires

49 and 50 and the other'part of the circuit is supplied with current from battery Z. V v

Delineated on Fig. 7 arethe bond wires connecting the corresponding terminals of the lines of instruments A, B, and D, on the switches F and C, which arrangement allows a call to be initiated on any line and perinits one to be received from an other line. These bonds leading to switch are designated as follows: A leading from the wire A to the contact A A leadin from the Wire A to the contact A; an the wire A, leading from the wire A", to the contact A In order to prevent the operation of the cut-off relays of those lines of the connector switch whose terminals are traversed by the brush 0", the circuit of said rush is opened during the rotary movement of the connector switch and it is to this end that the.

armature c is arranged on the local rela C. connected by the wire a, with the back contact 0", with which the spring switch a Aywire One end of the coil of this relay is i the movable member of the switch C, when the latter is in its normal position. The other end of said coil is extended by the wire'o to an armature a, on' the mate relay 51, which cooperates with a forward contact a, connected bythe wire 0 to the wire a, leading to the battery Z". The spring 0 is connected bv the wire 0 to a ground, Z" receiving impulses of current from the battery Z", from which it follows that," when the mate relay, 51 is energized, the following circuit is established: battery Z, wires 0 and 0", contact 0 armature 0, wire a, relay C wire o contact a, spring switch a, wire 0 to ground 2.", thus energizing the local relay C and opening the circuit of the brush 0", at the armature 0. A holdingcircuit is established for retaining current 1n the local relayv G, during the operation of the motor magnet 27, by connecting to the wire o an armature 0 which is attracted into engagement with the terminal 0 of the wire 0 which terminates in a back contact 0 of an armature 0 (on the line relay 41 connected by a wire a, with aground 2 also adapted to receive current impulses from the bat tery Z. This holding circuit may be traced as follows: battery Z, wires 0, 0 contact 0, armature 0, wire 0", relay C wire 0 armature 0, contact 0 jwire 0 contact 0, armature a, wire '0, to ground 2". Now, as both the relays C and 51 are so constructed as to discharge their residual magnetism slower than the line relay 41 does, the armatures 0 and e are held in attracted position during the vibration of the armature c and each movement of which supplies the current necessary to keep up the magnetism in the relay C until the pulsations of current over the line and mate conductors cease.

Upon the cessation of impulses from the impulse transmitter, A, the contacts A,

A thereof, are in engagement thus, leaving the telephone circuit closed and causing a break in the regularity of the transmission of said impulses, so that the line relay is energized holding the armatures c and a in attracted position. This interruption arrests the motor magnet 27 and allows the magnetism in the core of the relay C to seep or leak out, to close the circuit of the 55 cut-ofl' relay B, of the selected outgoing line.

Restoring the connector switch to normal.

lhisis-acc omplished by extending the circuit of each of'said magnets through an armature 136 which is attracted when the mate relay 51 is energized. This armature normally rests against the back contact Q, connected by a wire 0 with one end of the coil of the release magnet 36 and similarly connected by a wire a with one end of the coil of the release magnet 36 of the switch F. The other terminal-of the coil 36 is connected by a wire a, with a brush a, of a current interrupter, G with which cooperates the brush a, leading to the battery Z. The current interrupting devices of the switches F and C, are, in practice, one and the same, and the batteries Z and Z represent the source of current supply from a main battery-all as shown in Fig. 8. The armature 136 is connected by the wire o with the forward contact a, of the pair of contacts cooperating with the spring switch arm 0. This armature is also connected by the wire 0 to the armature f, shown in Fig. 6, on the relay F. When the connector switch has been actuated out of its normal position, the spring switch arm 0 engages the back contact, 0 and when the circuit over the line and mateconductors is broken, by the opening of the contacts at the subscribers station, such as A the armature 136 is released and engages the back contact a, completing the following circuit: (switch C Fig. 7 battery Z brush a, current interrupter C brush 0 wire 0 release relay 36, 'wire 0, contact 0, armature 136, wire 0 contact a, spring switch a, wire o flto ground a", over which the impulse or impulses, of current are sent to permit'the movable element of the switch C to return to its normal position. At this same instant the following circuit has also been completed: (switch F. Fig. 6) battery Z brush f, current interrupter F brush f, wire f, mag net 36 wire 0 (Fig. 7 contact 0, armature 136, Wires 0 0", (Fig. 6,) armature 7', contact f wire f spring arm f, contact f, to ground, .2 When the two switches, F. and C, are idle the armatures f? and 136 are each in engagement with their back contacts so that if the movable elements of either, or both, of the switches F and C are adjusted out of their normal position by manual manipulation, they will be returned by current operating the separate releasing magnets over the aforedescribed circuits. it will also be seen that if for any reason the finder switch F fails to pick up the line on which a call was originated, the movable eleinent will make a complete excursion over all until the incoming line has been picked up. It will be understood that this repeating movement results only when an unnatural condition exists, such as a delay occurring in the operation of one or. another of the relays, particularly the cut-oil relay of the calling line, which, might occur if the third brush, i of the finder switch, should fail to establish a circuit with the respective contact f, the first time it is stepped into engagement therewith. Likewise, if for any reason a subscriber should open the line by hanging up his receiver immediately after it had been removed from the hook, the finder switch would automatically return to its normal position in readiness to be again started upon an impulse of current received over the starting circuit branch of any of the incoming lines.

. Opening name. In exchanges serving a large number of telephone instrument circuits, the finder and connector switches are duplicated as many times as need be, and on each switch appear the terminals of the line and mate conductors, which may be extended as shown in dotted lines in Fig. 7, provisions not referred to herein, being made whereby, two or more connections may be set up at the same time. With such an arrangement of switches, it will be seen that where two line circuits are connected over one set of switches, the movable contact elements of another set of switches in traversing their coming line and also for the moment of time when both switches are released, and are returning to normal position. This is accomplished in the present instance by means of the two relays F, and F, each controlling a pair of armatures, one of each of said pair being located in the circuit of the line and mate conductors respectively. The relay F, has been described as being in the circuit of the wire f by means of which it receives current from the battery Z and is energized during the operation of the motor magnet 27*. The relay F is another one of the so-called slow or retarded relays, oneterminal of its coil being connected by the wire f to the wire f, the other end of the coil being connected by the Wire f, to the wire 0 whereby said relay is energized simultaneously with the release magnet 36 whenever the circuit of the latter is closed by current impulses transmitted from the current interrupter, F The armatures in the line conductor 4.- are indicated by 42 and 43, the former being connected to the wire 4 and coiiperating with the back contact, 44", joined by the wire 45* to the armature 43*, which normally engages the back contact 46, forming the terminal of the wire 4*. The armatures of the mate conductor 5 are indicated by 52 and 53, which are connected by a wire 5%, the former armature engaging a back contact or terminal 55 of the wire 5, and the. latter cooperating with the back contact or terminal 56*, of the wire 5*. When the two relays F and F are deenergized their armatures are in the normal position (shown in Fig. 6) and this part of the talking circuit is traceable as follows: line conductor 4, armature 42 contact 44", wire 45 armature 43 contact 46*, wire 4*; mate conductor 5, contact 55 armature 52,

wire 54, armature 53 contact 56 Wire 5.

Ringing and answering circuit.

The description thus far has been confined to the operation of the various elements which occur in the setting up of the connections between two telephone lines and to the mechanism operating conjointly therewith by means of which a connection is automatically broken and the switches restored to their normal position. There still remains for further consideration additional mechanism by means of which the signaling devices on the outgoing or called lines are operated, after the connection has been established, which are illustrated particularly in Fig. 9.

Each telephone instrument is provided with signaling devices, such as the usual ringer, (indicated by B, at station B, Fig. 9) which are energized by signaling current from the generator C, supplied to the out going line circuit, such as the wires BB In order to supply this current intermittently to ring the bells, or operate the signaling devices periodically, as well as to afford the. answering subscriber an opportunity to cut his instrument into the line, a signaling relay C is employed. This relay is rendered operative by the conjoint operation of the line relay 41 and the local relay C the latter acting to temporarily render the signaling relay inoperative and open the conductors between the source of signaling current and the movable contact elements, during the rotation of the brushes of the connector switch, so that the signaling devices of other circuits are not operated as the brushes of this switch traverse their terminals in seeking those of the selected line.

Dne end of the coil of the signaling relay C is connected by the wire 0 to an armaswitch picks up the outgoin ture a, which is attracted, when the balancing coil 5 is energized, into engagement with the forward contact a, of the wire 0 leading to the battery Z. The armature a when in normal position cooperates with a back contact a, connected, by .a wire a", to a brush 0 of the current interru ter C", the second brush a, of which is connected with the battery Z. The other extremity of the coil of the relay 1 is connected by a wire 0 to an armature 0 which is held in attracted position with aforward contact 0 when the line relay 415 is energized. The contact 0 is joined by the wire 0 to a back contact 0, of an armature c on the local relay C, said armature being connected to a ground 2 which completes the circuit from the rounded sides of the batteries Z and Z nstead of extending the line and

mate conductors

4 and 5* directly to the brushes C and C (as shown in Fig. 7) they are terminated in contacts 47 and 57 with which cooperate armatures 48 and 58 on the signaling relay C said armatures being connected respectively with brushes C and C by Wires 49* and 59 The brushes 0* and c of the current generator C are con nected respectively by wires 0" and 0 to aback contact a, of the armature 58, and an armature a, on the mate relay 51". The armature a", when in attracted position, engages a contact 0 connected, by a wire a, to a back contact 0 of the armature 48. It will be remembered that the line and mate relays 41 and 51*, are energized during all of the operations occurring on the connector switch, consequently when a line circuit is extended, to the latter, from the finder switch, the armatures c 'and c are attracted and held in engagement with their respective contacts and that when said called line the local relay C is deenerg zed, permitting thearmature to drop into engagement with its back contact, 0. The following circuit is then established: battery Z brush a, current interrupter C", brush a, wire 0 contact 0 armature 0, wire 0",.signaling relay C wire 0*; armature 0", contact 0", wire 0 contact a, armature a, to ground, 2

The last mentioned current interrupter C, is in practice, the same as C and F, and it serves to intermittently energize the signaling relay, which then attracts the armatures 48* and 58, in the line and mate conductors, in momentary engagement with the contacts 47 and 57". Now if it should happen that during the moment of time in which these armatures are attracted the subscriber should close his line at the receiver hook contacts B the following circuit will be established from instrument B to battery Z: battery Z, coil 4:, wires 49, a", contact 41 armature 48*, wire 49, armature 60, contact 61", wire 49, brush C, contact B wire B contacts 13 instrument B,

in the signaling relay C, which latter holds the aforedescribed line circuit closed until one or'both of the subscribers open the connected circuit between their two instruments.

In order to prevent the signaling current from being despatched over the outgoing instrument circuits successively, as the movable contact elements are advanced progressively, the parts 49 and 59 of the line and mate conductors are each provided with an opening adapted to be normally closed by arnlaturcs 60-T0 cooperating with contacts 6l -7l=h These armatures a re arranged on the local relay C and are attracted by it during the time the connector switch mechanism is selecting the given line circuit.

The arlnatures l8 and 58 normally stand in engagement with their back contacts and therefore the instant the wipers CC pick up the selected line and the local relay C releases the armatures G0--70, the ringing current is despatched from the generator C to operate the signaling devices I5 overthe following circuit, (shown in Fig. 9): current generator C brush 0, wire 0 armature 0, contact a, wire 0 contact 0, armatures 48*, 60, contact 61, wire 49, brush C, contact B wire B ringer B wire 13, contact B brush C wire 59, contact 71', armatures 58, contact 0, Wire 0, brush 0, generator C Multiple smite/Les.

The length of time required to set up a connection, or establish a call, may be greatly shortened or minimized by emplo v ing a multiple arrangement of tinder switches, preferably arranged in pairs, the equivalent sets of terminals on each being arranged relativelv in reverse position inthe banks of contacts on the two switches, which in practice gives the same result as would'be obtained if the mechanism of one switch of a pair was designed to drive its contact elements in a reverse direction relatively to the movement of the wipers of the other switch. The switch illustrated in Fig. 3 is provided with fifty sets of line circuit terminals, requiring fifty movements or steps-0t the wipers to bring them into ongagement with the last set of terminals. and. although the switch mechanism travels with considerable alacrity, it will be seen that the time required to enable the switch wipers to more into engagement with the last set of terminals, is twice as long as that consumed while the wipers are moving to the center of the bank of contacts to engage the twenty-fifth set of terminals. Consequently by tying each line circuit to two switches and either arranging the terminals thereon in inverse order or rotating the wipers of one of them in a relatively opposite direction to those of the other switch the total number of lines may be traversed in twentyfive steps thereby reducing the time to one half of that required by a single switch for making the selection of a line having the highest number.

To describe this idea more specifically: The circuit of instrument B was stated to be connected to the tortieth set of contacts, designated by L00 in Fig. 3, requiring forty steps of the finder switch F. On a second finder switch (such as F Fig. 10), the circult of instrument B would be joined to the tenth set of terminals, occupying the position designated by 100 in Fig. 3, so that the movable'contact elements of this second switch would only be required to move ten steps to select said instrument circuit. In Fig. 10 this duplication of finder switches is illustrated diagrammatically to show the arrangementof terminals corresponding to the circuits of instruments A and D,,-0f b'igs. 6 and 7. The switches]? and C are identical with those sliown in said figures, and the o 'ierating' mechanism-of the other finder switch F is like that of the switch F, but associated with it is a separate connector switch G which performs the same function as the corresponding switch 0, when an instrument circuit is selected by the finder switch F. It will benoticed that the sets of terminal contacts A"D" on the latter, are in reverse position in the switch bank, relatively to the corresponding sets A 7 on the switch F, while the sets of connector switch terminals D*D and it -A occupy the same relative position in the two switch banks.

The finder switch F is adapted to be actuated simultaneously with the switch F and to this end its sprin contact arm f is also connected to-all o the starting circuit branches by the wire i which causes both switches to start out to find a calling line circuit. The switch, the movable elements of which first pick up the terminals of said calling line circuit, will be arrested, as heretofore described, while the other finder switch continues its excursion. It will be rccollected that the instant the finder switch is arrested the cut-ofl relay of the calling line is energized, permitting the operating-holding circuit branch, (previously opened) to be closed. The closing of this circuit branch occurs before the movable contact elements or wipers of the other finder switch (which is still advancing) engage the second set ;oit terminals of the connected calling circuit. Consequently this finder switch is not arrested at said set of terminals but is permitted to pass over the entire bank of contacts until disengaging the last set of terminals when it is automatically returned to its normal position. If the finder switch F happens to be the one which picks up the incoming calling circuit then the latter is extended to the associate connector switch C which is operated to select the desired outgoing called circuit, the other connector switch C remaining idle.

In addition to facilitating the quick selection of an incoming calling circuit, as before mentioned, this duplication of the finder switches possesses the advantage of making the selection of a circuit doubly assured, for should the movable contact elements of one switch happen to miss a connection, due to corroded terminals, or a too rapid movement of the wipers, or some other unaccountable cause, then the other finder switch will pick it up.

Sub-station lamps.

To assist a subscriber in the manipulation of his impulse transmitter and the selection of other subscribers numbers, from his directory, as well as to inform him of the operativeness of his own instrument circuit, an incandescent lamp, such as A B -D, is located at a suitable point in proximity toeach instrument set. This lamp is arranged in the circuit of either the line or mate conductors which receive current whenever the instrument circuit is closed. The location of the lamp in the-instrument circuit is rendered possible by virtue of the arrangement of the switching mechanism which is controlled entirely by impulses of current transmitted over the two instrument circuit conductors and is not dependent for its operation upon earth connections, or a third line wire, cooperating with one or both of the usual line and mate conductors.

I claim as my invention:

1. In a telephone system, the combination with a switching mechanism comprising a plurality of terminals arranged in sets, separate contact elements cooperating with each of said sets, amotor magnet for operating them and a plurality of instrument circuits, of a motor magnet relay, a starting circuit for said magnet and relay and an operating circuit controlled by the relay, said circuit leading through one of the elements and comprising branches leading from one set of switch terminals and corresponding to each of the several instrument circuits, an actuating relay controlling each of said