US1109616A - Electrical signaling system for telephone-exchanges. - Google Patents

Description

E. E. CLEMENT. ELECTRICAL SIGNALING SYSTEM FOR TELEPHONE EXCHANGES.

APPLICATION FILED APE.12,1906.

1,109,616. Patented Sept. 1, 1914 4 SHEETS-SHEET l.

eluucntoz wx/w E. E. CLEMENT.

ELECTRICAL SIGNALING SYSTEM FOR TELEPHCNE EXCHANGES.

APPLICATION FILED APR 12.1906- Patented Sept. 1, 191-.

4 SHEETS SHEET 2 E. E. CLEMENT.

ELECTRICAL SIGNALING SYSTEM FOR TELEPHONE EXCHANGES.

APPLICATION FILED APR.12,1906.

Patented Sept. 1

4 SHEETfi- SHEET 8.

E. E. CLEMENT. ELECTRICAL SIGNALING SYSTEM FOR TELEPHONE EXCHANGES.

APPLICATION FILED APR.12,1906.

1,109,616. Patented Sept. 1, 1914 4 SHEETS SHEET 4.

EDWARD E. CLEMENT, OF WASHINGTON, DISTRICT OF COLUMBIA.

ELECTRICAL SIGNALING SYSTEM FOR TELEPHONE-EXCHANGES.

Specification of Letters Patent.

Patented Sept. 1 1914.

Application filed April 12, 1906. Serial No. 311,388.

To all whom it may concern:

Be it known that I, EDWARD E. CIJEMENT. a citizen of the United States, residing at \Vashington, in the District of Columbia. have invented certain new and useful Improvements in Electrical Signaling Systems for Telephone-Exchanges, of which the following is a specification, reference being had therein to the accompanying drawing.

My invention relates to electric signaling systems, and particularly the combination of such systems with telephone exchange systems in such manner asto enable both to be used for their proper purposes without interference. Composite systems answering this general description have been known for a long time, but many objections have been urged against them, and except in connection with long lines where the necessity of realizing on a heavy investment has proved compelling, they have not come into general use. One reason for this has been that none of the systems heretofore proposed has been applicable to standard common battery telephone circuits without increasing the liabilitv to derangement thereof. In all the systems heretofore proposed, it has also been necessary to install complicated and costly apparatus at outlying points, such as the subscribers stations. In my present system I avoid the necessity for this, concentrating all the important apparatus at a central point, referably the central office of a telep one exchange where it is under constant supervision and is easy of access.

Briefly stated, my invention comprises a special signal and telephone trunk from the exchange to fire or police headquarters, or elsewhere, and there provided with the usual registering apparatus. operated preferably on a closed circuit, so that constant test is on the trunk. This trunk terminates at the exchange in the bus-contacts of a primary selector switch, preferably constantly running. Each line which is to be employed for signaling has multiple branches tappe off from its c'entral otiice talking terminals to a pair of contacts in the switch, and also has a local circuit branch taken from the line-relay t0 the switch. The only addition I make to the telephone equipment is an extra line-relay at the central ofiice, and a circuit-closer or a thermostat out on the line. The line-relay controlling the line-signal on the telephone switchboard is connected on the grounded or idle side of the battery. The additional or second line-relay is connected between the line and the live side of battery. \Vhen the subscriber calls in by taking down his receiver from the hook, both these relays pull up. The special relay close: the signal branch to the fire-alarm trunk, but the regular line-relay simultanel ously'opens the same branch. at the same time setting its signal on the telephone switchboard. Such a call does not get on to the special trunk at all. On the other hand, if one of he circuit closers is operated so as to put station. the switchboard-relay will not operate. but the extra relay being on the live side of battery will do so. The branch signal circuit to the primary selector switch is thereby closed, and the switchboard signal circuit remains open. The primary selector switch in its rotation tests one line after another, and when it comes upon the terminals of thiscalling line it stops and connects the same at once to the trunk. This trunk has condensers and branched sleeve relays arranged in the same way those of the operators cord-circuits. Hence when the trunk comes onto the line-terminals battery is supplied as usual to work the cut-off relay of the line, and to raise the potential of the jack-thimbles so that the line will test busy on the switchboard. Associ ated with each set of line-terminals in the primary selector switch is a pair of signaling pens controlled by a number-wheel having its teeth arranged to transmit the number of the line. If there are one hundred lines represented in the primary selector switch there will be one hundred of these little wheels, which I preferably arrange on a common spindle to be constantly driven along with the switch. The tip relay of the trunk opens the normally closed signaling circuit and immediately the number commences to go in, being taken up and registered by the dew-"1s at headquarters. At

a ground uII the line at the subthe same time the subscriber having removed is a similar diagram showing a slight modihis telephone receiver, the telephone at headquarters may be taken down and conversation proceed without interfering at all with the signal. The subscriber may give his number or the location of his residence and such other information as headquarters may require. so that instant action may be taken without waiting for the completion of the registered signal. \l'here oral communica tion is thus the primary object, the subscril'tcr need not be compelled to maintain the ground on the line at his station, and for this purpose 1 may make the special line relay at central self-locking through a back contact on the cut-oifrelay, so that it will stay up until the trunk circuit is on the line, when it will be cut otf. At the'same instant that this is cut off, a separate controlling winding on the selector switch receives battery through the contacts of the tip relay of the trunk, which corresponds to the supervisory or tip relay of the operators cords. Hence the further connection is under the control of the subscriber, and the primary selector switch is released and all parts restored to their normal position as soon as the subscriber hangs up. For signaling purposes alone, and especially where the signals are to be sent automatically as by thermostats or burglar alarm circuit closers, the subscribers telephone receiver need not be taken down, and in such case the ground is of course maintained on the line until the instrument which caused it is reset by hand. as usual. The special relay in this case need not be self-locking, and the tip relay of the trunk is controlled by the persisting ground at the substation so as to maintain the connection until the latter is removed. Otherwise the arrangement and operation are the same as where the special telephone service is required and of course the two may be combined to advantage. as neither use of the wires interferes with the other. The trunk-line to fire or police headquarters may he an original metallic circuit telephone line, provided with a jack, cut-oil relay, c'tc., on the telephone switchboard. The amount of apparatus required in the primary selector relay sets is comlmratively small. so my entire system of signaling may be installed in a telephone exchange without disturbing the ordinary business, and at comparatively small expense. while its efliciency is rela tively the same as that of the best standard telephone system.

My invention is illu trated in the accompanying drawings. in which- Figure l is a title elexation of a primary selector switch en'iployed in my invention;

Fig. 2 is a cros -sectional view of a portion thereof; Fig. 3 1s a top plan view thereof; Fig. 4 is a diagram of the system; Fig. 5

fication of the circuits.

Before proceeding to the circuit connections and the operation of the system, I will briefly describe the novel apparatus employed. This is shown in Figs. 1, 2 and 3, representing a form of switch capable of serving one hundred subscribers lines. The design is that each line shall be represented by a terminal in this switch,-which may be located at the central telephone exchange or at any other convenient point where the lines are all accessible. The line connection to the switch does not interfere at all with the telephone switchboard or signal connec tions, but the subscriber has it in his power to differentiate between signals intended for the switchboard and those intended for the tire-alarm or police headquarters. \Vhen he produces the necessary change to send a signal to the fire-headquarters, theterminals of his line in the primary selector switch are thereby rendered active, so that the switcharm in its revolution becomes actuated when those terminals are reached, connecting the same and thereby connecting the line calling to the switch trunk, which leads to the fir alarm or police headquarters or any other desired point.

In Figs. 1 to 3 I have shown a single switch mounted in a frame, but obviously in practice I may employ any desired number of said switches. S the switch, having a base-plate, 8, carrying vertical standards, 8, connected at the top by a spider, 8 having three arms retired to the standards and a central bearing for the upper end of the vertical spindle, a This spindle as shown has its ends provided with depressions, which receive and turn upon the points of center screws, 828, both screws being adjustable and provided with locking nuts. Supported Within the frame upon brackets, s, is the circular contact-bank, 8 comprising upper and lower plates. a and .9 connected by screws, s and clamping between them the circular series of contacts with rings of'interposed insulation. These springs are in sets, each set appertaining to one particular line, and comprising the following: an upper individual spring, a, for testing purposes; a lower trunk ring, 8, a pair of talking circuit line-springs, 8 s; a pair of trunk talking circuit springs, 8 and a pair of line-number signal springs, s and a. 'ithin the ring of contacts the spindle, s is provided with a gain or annular notch, in which lie the edges of a pair of plates, and a, screwed to the iron head of an lectromagnet, 8 which is Wound on a brass or iron tube surrounding the spindle. Thespindle itself forms the core of this magnet, and passes through. an' opening, 8

Referring to these figures,

in the armature, 8, thereof, which is pivoted to the iron jacket of the magnet at 8 and carries the bell-crank leverarm, 8 whose upper end extends through a slot in the bottom of the tube, 8 and a registering slot in the plug, 8 of insulating material. As the armature is pulled up it throws out the plug, a, so that it passes between any pair of springs, 8 a. to which it is opposite. At the same time, it withdraws the pin. 5 from its normal resting place in a notch in the disk, .9, which is rigidly secured on the spindle, .9 In order to maintain the armature down and the plug, 8 retracted, as well as to furnish means for testingthe line-contacts, s, I provide the strong spring, 8 secured at its lower end at the angle of the bell-crank armature lever, and steadied at its upper end by being perforated so that the plug tube passes through it. A companion spring, a, constitutes a sliding contact which is in constant engagement with the trunk ring, .9 and these two springs s and s are connected to two separate windings of the magnet. .9 the inner ends of both of which are grounded on the spindle. The first winding, being connected with the spring, .9 takes current when that spring comes on a calling contact. This pulls up the armature, stops the rotation. of the magnet, and at the same time throws out the plug, 8 between the springs s 8 of the set corresponding to the calling line, connecting the contacts, s 5 of the trunk thereto. The trunk contact, 8 takes current at this time controlled by one of the trunk relays, and hence as long as that trunk relay remains active current passes through the ring, 8 the spring, a, and the second winding of the magnet to the spindle and ground. The trunk relay is controlled by the calling subscriber, and as it becomes active the subscribers line cutofi' relay is also energized, so that the line spring, 8, becomes dead, and at the same time the jacks of the subscriber on the telephone switchboard have their potentials raised in order that they may test busy.

Having thus described the apparatus, I will proceed to explain the diagram in Fig. 4. This shows a subscribcrs station A, having the usual telephone transmitter, receiver, switclnhool-I, hell and condenser: and also having a pusl button or key, K, for making special calls. The station. A, is-connected to the central oflice by the line-wires 12 and the sole function of the key, K. is to ground the line-wire 2. .\t the central ofiice these linewires p ss to the contacts. n, M, of the cutoil rel av, and u normally prolonged therethrough to the two line-relays. M, M. The

'first of these controls a local circuit including the switchboard lamp, L, associated with the answering jack, J. It also controls jointly with the second line-relay M the continuity of the wire 3 leading to the contact 8, representing the line 12 in the switch, S. The relay, M, is self-locking, and is connected between the line and the live side of battery. By self-locking I mean that when it pulls up by reason of a ground on the line, it grounds itself through the wire 4, through a back contact on the armature. n, of the cut-off relay. N, so that if the key, K. is even momentarily depressed, the relay, M. will pull up and stay up until connection is eilected with the trunk and the cut-oii' relay. N, thereby becomes energized. The wire 3 passes to a front contact of relay, M, associated with the armature, in, which is connected to a back contact of the armature, m. of the relay, M, this armature iii-turn being connected through the wire 5 to the live side of the main battery, B.

In order to illustrate the telephonic side of the system, I have shown a second subscriber-"s station, A, equipped in the usual manner, and havi; g a jack, J, and a lamp, L, on the telephone switchboard. To interconnect these lines at the switchboard I provide the usual plugs, P, P, connected by the cord-conductors. (3, 7, fl, 9, provided with the condensers, C, on opposite sides of which are bridged the sleeve and tip relays, R, R, R R controlling the supervisory lamps. If, If. Each jack, J, or J, has its cnitacts connected by wires 11 and 10, res e tively, to the front contacts of its cutofi relay, so that when the latter is energized the line is extended to the jack. Connected in parallel with the jack contacts, are the wires 12 and 13, which pass respectively to the contacts. 8 and s of the line set in the switch S. From the associated springs, 8 s. extend trunk- wires 14 and 15 leading to the condensers, C, from the other side of which the wires 16 and 17 pass to the firealarm or police headquarters, H. The wires are shown very short in the drawing, but the wavy line marked 18 indicates that portion of the circuit extending between the telephone exchange and headquarters. the circuit-Wires 1G and 17 for this portion being ofany required length. The circuit 1617 comes into headquarters and is there connected to the telephone set in precisely the same manner as at any other station, The ine is also preferably provided at the cen tral ot ce with a jack, J similar to those of the subscribers lines, whereby the headquarters can be called from central in the usual way. The magnet I may also be used as a line relay and a suitable cut-ofi' relay provided, together wit cal i g key adapted to break the circuit at the substation, all in a well known manner, being a mere reversal from open circuit to closed circuit Working, and making the headquarters line a subsc'ribers line to: switchboard calls, I

prefer, howe; er, to have this particular cir cuit made special, and not subject to the same limitations, busy tests, etc, as the ordinary subscribers line, for the obvious reason that when a subscriber sends a fire or police signal it must be made special, and should not be subject to ordinary delays or risks.

Tapped off from the two sides of the line 1617 at headquarters are the branch wires 1920 containing the choking coils, I, I, which are wound so as to have a compara tively low ohmic resistance, but a very high inductive or apparent resistance for voice and similar currents. From a common point 21 between these two coils I take off a ground tap 22 through the register relay, R controlling the Morse register, B In accordance with standard practice, the special alarm circuit is worked on the closed circuit principle, that is to say current is maintained normal thereon, and the relay, R", is therefore constantly energized, keeping open the local circuit 23 of the Morse register. In case of trouble on the line, such as a short-circuit or a cross, the relay will lose current, and the register make a continuous line on the tape, a constant test being thus provided. The register also re- .eords the number of any telephone line or substation which calling headquarters, and this record is made automatically whether the telephone is in use or not. In fact, with the arrangement in Fig. 4, the subscriber must first press his key, K, in order to call headquarters, and then immediately take down his receiver and the very instant his line is through to headquarters he may converse with the operator there, while the number of his station is being simultaneously recorded on the tape. The transmission of this number is accomplished in the following manner: A number of individual signal wheels, 8 one for each line, is provided, each having teeth on its periphery corresponding in number to the code number of its subscribers line. These wheels are preferably constantly driven, and may all be on one common shaft or on a series of trunk shafts, but it is not essential that they be constantly driven. They ca be driven in any desired manner, the only desideratum being that each wheel must turn when its line is calling.

When a call comes in for headquarters, and the switch, S, connects the wires 12-13 to the trunk 14-45, by plugging in with the plug, 8 it also closes the two springs, a", s together, thereby completing the signal (-11-- cuit 25, 26, 27, 28, leading to the two sides of the line 1617 through the choke coils, 1 I". The continuity of this circuit is con trolled by springs, 8 which are opened and closed by the wheel, 8, in its rotation. The tip relay, R of the trunk, which has been already referred to as controlling the second winding of the switch magnet, 8, during operation, is also employed to keep the signal circuit normally closed and battery normally on the trunk-line, through its back contact 29 and the branch wires 30 and ill. The wires 30 and 25 are connected back to battery through the wire 32, and the sequence of operations therefore is follows: 'hen the calling line first comes in on the trunlc, the relay, R pulls up, taking battery oli' branch 31, and at the same time the wheel, 8, starts, thereby sending pulsations of cura rent over the line-wires lo -l4 which will print the code number of the calling station on the tape of the Morse register, The wheel, a, may or may not continue ro tating as longas the line is on the trunk, but if desired the operator at headquarters may be provided with a switch S to cut off the wire 22 or break the circuit 23, or the equivalent thereof, so as to prevent the continued operation of the register.

The further details of the system will sufliciently appear from the following statement of operation: Vr'e will first assume that subscriber A desires to make an ordinary telephone call. In order to do this he takes down his receiver in the usual n'u'inner, thereby closing his metallic linocircnit, and supplying current to the line-relay M by the following route: B, 5, M, if, 2, substation, l, n, M, and ground. Both the relays, M, M, will immediately pull up, the former putting battery on the lamp,L, but no etlect being produced by the other relay, for the reason that at the same time that the armature, in, connects battery to the wire 3, the armature, m, disconnects it. Hence the only signal is on the telephone switchboard where the plug, P, is inserted in the jack, J, the number obtained, and connection effected with any other desired line through the plug, P, and the jack J. Assuming, however, that subscriber A desires to call headquarters he presses button, K, removes his receiver from the hook, and waits. This grounding of the line-wire 2 completes the following circuit for the relay, M B, 5, M, if, 2, K, and ground back to battery. The relay, M, immediately pulls up, completing the following circuit: for locking itself, B, 5, M, 4, armature a and ground; for getting in on the trunk, B, 5, m, m, 3, a and when the plug comes around opposite that spring, through the contactspring, s and wire 40 to the actuating windings, of the switch-magnet, to the frame of the same and so to ground. The release of button K does not cause operation of the relay M because the line limbs 1 and 2 are short-circuited through the locking circuit of relay M. The magnet immediately pulls up its armature, thereby uncoupling itself from the spindle, s and throwing out the plug, .9 into what I may call the jack springs of the calling: line. The springs, 8 s and s", are moved to make contact respectively with a. 8" and a. Th line extensions 12, 13 are immediately connected to the trunkwires l-t and 15 through the springs, 8 a. 3" and s A circuit through the sleeve side of the trunk is therefore ch sed as follows: i i, 3:2, It, 15, s s 13, cut-ofl' relay X and ground back to battery. The cut-oil relay tlief-seupcn pulis up, the lQnlStilllCQ of the windings It, Rfin the trunk bridge being substantially the same as that. of the re iays R. R in the cord-circuits. The relays, M, M, are thereupon cut oif, the locking circuit 4 of the latter being broken. As this occurs, hmvever, the relay R has pulled up in the trunk, and thereafter remains sub ject to the act cf subscriber A. This relay maintains the Locking circuit for the switch magnet closed as follows: I 32. armature of It", 42, s. a, 4.1. winding, 8", frame of magnet and to ground back to battery. It will be observed that this places the continued control oi the switch in the hands of the calling: subscriber. the relay R corresponding in fact to the supervisory relay ot a cordcircuit. As long as the subscriber keeps his telephone ed the h ok the switch will be maintained in the position to which it is set, but as soon as he hai'igs up his receiver and thereby disrupts his line-circuit, the relay will let go and the switch wi l be released. li'hen the relay, R pulls up. it breaks the signal circuit 30. 29 ii. .27. '28. Ni, 17. 20, 19, ll. The brat-i i circuit 26 has been connected to the wi e i wcver, through the springs, .9". in the switch, and the individual signabwheel springs. a. At the same time the wheel. a, is caused to act upon the springs a. which are brought together and separated in accordance with the code arrangement: cf the teeth on the wheel. Each time the springs are pres ed together the following circuit is clcscd: Pt. 32, 25. s, e, a. 2c, 27, 28, 16. 17,20, 19.21. 22, It. and ground back to battery. Each closure pulls up the armature of relay, R opens the circuit 23 and deenergizes the magnet of the register. R Conversely, each break in this main signal circuit deenergizes the relay, R. closes the circuit 23. and causes the register to make a mark on the paper. ot parts at all. I can adjust. the springs 8 so that they will be in constant contact, and momcntarily separated as the teeth of the wheel pass over them. this is a better mode of operation, sirr'e the relay, R, is then maintained energized eX' cept when the teeth are passing, and each tcotb produces a mark on the paper nstead ot' each gap. llowcver, this is a detail of arrangement which may be varied according to the nature of the register or the wishes of its operator. The signaling current being lVithout chan in the arran 'ement h f h In some respects.

thus sent in parallel orer the two sides of the trunk, 16- 17, the same are at equal potentials, and if the coils, I, I, I and I are properly balanced, the code impulses will be almost if not quite imperceptible in the receivers connected across the metallic circuit. I think it somewhat desirable to have these impulses ;-.lightly audible, because they atl'ord the subscriber a convincing proof that his signal is going in. The combination is also an excellent one for the operator at headquarters, for the reason that while recording the tape he may converse with the subscriber and check up any excited or mistaken statement of location by the code number.

Fig. 5 shows a slight modification of the circuits in which the signaling feature is rendered the most important, and the re moral of the subscriber's receiver or oral communication on his part with headquarters is rendered unnecessary. As usual in thermostatic and other protective systems, the grounds at Th and Ba persisi until the instrunients are manually reset, or until conditions are removed which caused them. The special line relay at central need not be self-locking therefore, and the tip relay R of the trunk is connected to battery instead of ground. Com'ei'satjon may be carried on over this circuit the same as over that of Fig. 4. but is not essential. and the trunk will remain connected with the line until the ground irtaken oi? at the substation.

I have indicated the transmitter at the l'ieadquarters' station H as being in a local circuit with its own battery, but of course this arrangement is shown merely for convenience. I may arrange this telephone in any desired manner. I should also state that the relay, It, may be connected to the trunk n other ways than that shown, present practice including many arrangements which are well known to all telegraph engineers. Similarly, the apparatus controlled by the relay. R". may be varied in many ways equally well understood. For example, if H represents the regular headquarters of the tire department of a city, there will be what is known as a repeater, which responds to a signal over any one loop in the city firealarm circuits, locks out all the other loops for incoming signals, and repeats out over them all the signal from the active loop.

In the present diagram the relay, R", instead of merely controlling the register, may be the appropriate relay of the repeater, all the telephone lines coming in on the trunk 16l7 thus constituting one loop in the fire-alarm system. The wires 1415 may also be multipled to more than one switch, S, so that more than one set of linecontacts, or more than one hundred subscriber's, may be served. Each relay, R, may control the repeater, one the relays, 1 30 R, of a number of trunks 16-47 may have a relay under their common control, and this in turn control the repeater. I should also point out that many variations are possible both in the switch. S, and in the grounding circuit-closer, K, at the substation. I do not wish to limit myself to the rotating switch, S, or indeed to any particular form of switch. As regards the circuit-closer, K, the key herein shown is merely typical. It will be quite obvious to those familiar with the art that the ground may be put on the wire 2 by thermostats, or any one of a number of push-buttons ar ranged in parallel, by circuit-closers or windows or doors, or in fact by any of the well-known means employed in burglar, fire, or general signaling systems. This leads me to a further explanation. I have shown line 1-2 as capable of being automatically put onto a trunk leading to headquarters H. This is all that is necessary for an understanding of the invention. Multiplication of this arrangement, however, gives me a number of possibilities. For example, in practice I provide a number of the trunks 16-47, some of which go to fire headquarters, others to police, and others perhaps to some other point requiring special connection, such as the chiel clerks oflice in a Government department or the like. Different telephone lines may be connected to the switches of difi'erent trunks, so that some of the lines can call fire headquarters direct, others police headquarters. and others again can reach the chief clerk or captain of the watch or what not without going through the switchboard. In some of the Government departments at \Vashington, it is usual to have what is known as a crank call. This consists of a special push-button circuit leading from the office or offices to be protected, to the guard room or ofiice of the captain of the watch. According to my present invention such serv ice can be given without running any special wires, by merely adding the necessary apparatus to the existing telephone lines.

The most important feature of this in\ ention, broadly stated, lies in the power of a subscriber to connect himself at will with either a switchboard or a special signal circuit, that is to exhibit a signal at either place according to his necessities. I am aware that arrangements have been proposed in the past whereby a subscriber could signal any one of several different switchboards or switchboard sections, also where-- by in a fire-alarm system special signals would drop a special -a]arm device in a joker circuit so as to send desired impulses into the gong or releasing circuits. In the first place, however, the subscriber merely signals to switchboard operators in all cases, being dependent upon them for his service,

fact a tree-wire of the old-fashioned Law 80,

type can be substituted for the ground. In any case the apparatus at the substation is not complicated, the only addition to the telephone set being some form of circuit-closer.

Having thus described my invention what I claim and desire to secure by Letters Patent is 1. In a composite telephone exchange sys- .-'\ccording tem, a plurality of telephone lines, and

switching means to interconnect the same for conversation, of an automatic selective device having individual connections to the several lines, a code signal receiving station connected to said selective devicc,and means controllable in the use of any line to actuate said selective device to connect the line to said code signal receiving station, together with an automatically operating code transmitter arranged to transmit impulses to said receiving station according to a predetermined code upon the connection of any line with said signal receiving station.

2. In a composite telephone exchange sys tem, a plurality of telephone lines and means for interconnecting the same for conversation. of an automatic selective device containing individual terminals for the several lines, a special substation telephone circuit permanently connected to said selective device. and means operable over any line to actuate said selective device and connect the I line to said telephone circuit.

3. In a composite telephone exchange tem, a plurality of telephone line-circuits, a 1 5 central oflice switchboard containing terminals, line-signals, and connective apparatus for said lines, a common code signal rece1vmg circuit. and a separate selective switching mechanism .also containing termlbals of said lines and adapted to be actuated over any one of the lines to connect it with the common code signal receiving circuit, together with an automatically operating code transmitter arranged to transmit impulses to said receiving circuit according to a predetermined code upon the connection of any line with said signal receiving circuit.

4. In a. combined telephone and code signaling system, a plurality of telephone cir- 13o cuits, a central oflicq switching equipment containing terminals and connective devices for said circuits. a separate selective switching apparatus also containing terminals of the lines, code signal receiving means with a trunk circuit therefrom to said selective switching apparatus, and means operable over any line for selectively initiating con nection of the line either through said connecting equipment, or with said selective switching apparatus, together with an automatically operating code transmitter associated with said selective switching app aratus and arranged to transmit to the said' signal receiving means signals according to a predetermined code upon connection of any line with said switching apparatus.

5. In a combined telephone and signaling system, a plurality of telephone lines, a central oflice switchboard for interconnecting the same for telephonic purposes,line signals thereat, a separate, special and additional selective switching apparatus normally in disuse but common to a plurality of lines for connecting the lines outside of the telephone switchboard for signaling purposes and embracing actuating means, means responsive to current changes in each line for operating the line signal to efl'ect a call at the telephone switchboard, and means also responsive to current changes in each line for operating the separate switching apparatus to effect a call outside the switchboard,

at will.

6. In a combined telephone and signaling system, a plurality of telephone lines, a central ofiice switchboard for interconnecting the same for telephonic purposes. a separate switching apparatus for connecting the lines outside of the telephone switchboard for signaling purposes, means dissociated from the aforesaid switching apparatus responsive to current changes in each line for operating the line signal to effect a call at the telephone switchboard, and means also responsive to current changes in each line for operating the separate switching apparatus to effect a call outside the switchboard. at will.

7. In a combined telephone and code sig naling system, a plurality of telephone lines, a central ofiice switchboard containing terminals and line-signals for telephonic circuits, a common code signal receiving circuit. a separate switching apparatus also containing line-terminals and adapted to connect the lines individually to the common code signal receiving circuit, and means whereby a call may be sent over any line from an outlying point and auioma-tically directed to the telephone switchboard or through the separate switching apparatus to the common code signal receiving circuit, in each case exclusively, together with an automatically operating code transmitter associated with said separate switching apparatus and arranged upon actuation thcreoi in response to a call from any line to transmit over said code signal receiving circuit impulses according to a predetermined code.

8. In a combined telephone and code signaling system, a plurality of telephone lines and a link circuit common to a plurality of lines for interconnecting the same for telephonic transmission, together with a code signaling circuit, means for individually sclecting and connecting the lines to said code signaling circuit for code signal transmission, and means controllable over each line whereby a call may be distinctively directed to one or the other set of circuits at will, together with a code transmitter arranged upon connection of any line with said code signaling circuit to transmit thereover line identifying code signals.

9. In a combined telephone and signaling system, subscribers lines each having a line terminal and a pair of signal magnets. switchboard apparatus for cfl'ccting connection with said lines for conversational purposes, a selective switching apparatus for effecting connection with a line to receive special signals, said magnets acting rcspec tivcly to control the line connection through the switchboard apparatus and through the selective switch, and means at the subscriber's station for selectively controlling said magnets.

10. In a combined telephone and signaling system, a plurality of subscribers lines. a telephone switchboard for interconnecting the same for telephonic purposes. individual line signals on said switchboard, a separate signal switch containing terminals. of the lines and having a common signal receiving circuit. and line-relays respectively controlling the switchboard signals and the signal switch. together with means under the control of a subscriber for selectively energizing said relays.

11. In a combined telephone and code signaling system. subscribers lines, a central exchange provided with line terminals, signals and connective apparatus. and an automatic selective switch adapted to select calling lines also connected with said lines, with aspecial code signal circuit associated therewith, means at a subscribers station for operating said line signals. and other means at said s'ubscribers station for operating the automatic switch independently of the line signals, to connect a selected line to the aforesaid special code signal circuit, together with a code transmitter arranged upon operation of said automatic switch from any l ne to transmit line identifying code signals over said special signal circuit.

12. In a combined telephone and code signaling system, a plurality of line circuits, at central oflice switchboard containing terminals of said line circuits, line signals associated therewith, and connective apparatus for the lines, a code signal receiving station, a selective switching mechanism also containing terminals of a plurality of the line circuits, a trunk line connecting said switching mechanism with the code signal receiving station, and means under the control of each line circuit for operating said selective switching mechanism, together with an automatically operating code transmitter arranged to transmit line identifying signals to said code signal receiving station.

13. In a combined tele hone and code signaling system, a plurality of line circuits, a central oiiice switchboard containing terminals of said line circuits, line signals associated therewith. and connective apparatus for the lines, a code signal receiving station provided with code receiving apparatus. a selective switching mechanism also containing terminals of the line circuits. a trunk line connecting said switching mechanism with the code signal receiving station, and means under the control of each line circuit for selectively actuating either its switchboard signal, or said selective switching mechanism, each to the exclusion of the other, together with an automatically operating code transmitter arranged to transmit line identifying signals to said code signal receiving station.

14-. In a combined telephone and code naling system. a plurality of subscribers lines, means for interconnecting the lines for nversation. a special code signaling circuit. and an automatic selective switch controllal'ilc over any of the sul'iscriloers lines to connect said special code signaling circuit tliwcwith. together with an automatically operating code transmitter arranged upon connection of the code signal ing circuit with any line to transmit over said signaling circuit line identifying code signals.

15. In a telephone exchange system. a 'ilurality of subscribers lines terminating in a given point. means normally in use for intcrcoimwting the lines for conversation, a special service trunk line' independent of and dissociated from the aforesaid means and extending to another point. and an au tomatic selective switch also independent of and dissociated from the aforesaid interconnecting means but adapted to connect the trunk with any of the subscribers lines.

16. In a telephone exchange system, aplurality of line circuits, manual means for interconnecting the same for conversation, and auton'iatic switching means independent of and dissociated from the aforesaid manual means constituting the answering terminal of a special service circuit, and adapted to associatethe same with any of said line circuits.

17. In a telephone exchange system, aplurality of line circuits, a trunk circuit, means for interconnecting the lines for conversation, and separate automatic switching means independent of and dissociated from the aforesaid interconnecting means and arranged to connect the line circuits individually and exclusively to the trunk circuit.

18. In a telephone exchange system, aplurality of line circuits terminating at a given point, manual means for interconnecting the same for conversation, a trunk independent of and dissociated from the aforesaid manual means and extending to another point, automatic means constituting the answering terminal of said trunk and controlled over the line circuits to connect the trunk to any of the same, and an automatically operating code transmitter arranged upon connection of the trunk to any line to transmit over the trunk line identifying signals.

19. In a telephone exchange system, a plurality of line circuits, aplurality of separate switching equipments therefor, one at least of which is an automatic switching equipment, and means individual to each line and operable thereover to selectively and exclusively direct a. connection of the line to one or the other switching equipment.

20. In a telephone exchange system, aplurality of line circuits, means for interconnecting the same for conversation, a common substation telephone circuit, and an automatic switching device constituting the answering terminal of said common substation telephone circuit, separate from the interconnecting means common to all the said line circuits, and responsive to calls over the lines to connect the same individually with said telephone circuit. together with a code transmitter arranged upon the connection of any line.with said common telephone circuit to transmit thereover signals according to a predetermined code.

21. In a telephone exchange system, aplurality of line circuits, means for interconnecting the same for conversation, a common code signal receiving device, and an automatic switching device separate from the interconnecting means and common to all the said line circuits responsive to calls over the lines to connect the same individually with said code signal receiving device, together with an automatically operating code transmitter associated with said automatic switching device and arranged upon connection of any line with said signal receiving device to transmit thereto line identifying code signals.

22-. In a telephone exchange system, a line circuit, a central ofiice line relay (zoritifoll a-v ble thereover, a souree of"-'eu'rrent for the relay, means for closing the line to: energize the rel-(Ly, selfelockin contacts on the relay, a local locking,cireuiteleetrically separate from the line closed thereby, with a cut-off relay having :no'r'mally closed contacts included in the eoniieetions from the line circuit to the line relay," and other normally closed contacts includedin saidlocking cir- 10 cuit; and adapted to be opened when connection is eflected with the line.

In testimony whereof I aifix my signature in presence of two witnesses I V EDWARD E. CLEMENT.

'Witnesses:

E. EDMONSTON, Jr., JOSEPH L. WRIGHT.

five cents each, by addressing the Commissioner of Patents,

Washington, D. C.

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