US683569A - Automatic signaling system for telephone-exchanges. - Google Patents

Description

No. 683,569. Patented Oct. 1, 19m.

J. L. MGDUARRIE. AUTOMATIC SIGNALING SYSTEM FOR TELEPHONE EXCHANGES.

,(Application filed. Jan. 26, 1901.)

.(No Model.)

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UNITED STATES PATENT OFFICE.

JAMES L. MCQUARRIE, OF CHICAGO, ILLINOIS, ASSIGNO R TO THE XVESTERN ELECTRIC COMPANY, OF SAME PLACE.

AUTOMATIC SIGNALING SYSTEM FOR TELEPHONE-EXCHANGES.

SPECIFICATION forming part of Letters Patent No. 683,569, dated October 1, 1901.

Application filed January 26, 1901. Serial No. 44,906. (No model.)

To all whom it may concern.-

Be it known that I, JAMES L. MCQUARRIE, a citizen of the United-States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvementin Automatic Signaling Systems for Telephone-Exchanges, (Case No. 13,) of which the following is a full, clear, concise, and exact description.

My invention relates to a telephone-exchange system, and concerns more particularly the operators central-oflice apparatus for making connections between two telephone-lines, my object being to substitute automatic devices for doing a share of the work which has hitherto been done personally by the operator, and so to economize the operators time and enable her to handle a much larger number of connections than has hitherto been possible. Y

\Vith telephonecxchange systems at present in use the operator finds it necessary to ring the called party a definite number of times or a definite length of time, and if no response is had she must connect her telephone with the calling-line and report to the calling subscriber that no answer has been made to her signal. Usually the calling party asks that the subscriber wanted be run g again,

being the insertion of the calling-plug in the jack of the called line.

The invention may be generally described as comprising a source of peculiar oi characteristic signaling-current, (which may be a phonograph-transmitter, a musical-tone-producing transmitter, or the like,) a switch for connecting the same with the calling-line, a time device operated or set in operation during the application of-ringing-current to the called line, and means controlled by the time device for actuating said switch. In the preferred embodiment of my invention the ringan electromagnetic step-by-step device responsive to the intermittently-applied ring-. ing-current advances a predetermined number of steps and then actuates a switch which disconnects the ringing current from the called line and connects the peculiar signaling-current with the calling-line. The call-. ing subscriber listening in his telephone thus hears after a given time either spoken words from a phonograph, such as They dont an,- swer, or a peculiar hum or tone, which he recognizes as meaning that the called party has not responded. He will then hang up his telephone, and the usual supervisory signallamp at the central office will be lighted, giving the operator the signal to disconnect.

The apparatus of my invention will be useful either at a trunking-board or B posiing-current is periodically interrupted, and

tion, where calls are received over trunklines from distant boards, or' at an answering-board or A operators position, where:

the call comes directly from the subscriber..

I will describe my invention particularly by reference to the accompanying drawing,

which is a diagram illustrating two telephone-lines extending from a substation to a central office, with the operators apparatus for connecting the lines, equipped with the signaling apparatus of my invention, and the features which I regard as new will be pointed out in the appended claims.

The two telephone-lines illustrated, ex-

tending from substations A and B to the central office C, are equipped with the usual substation and central-office apparatus, the system being of a well-known type, in which a central source of current is connected withv all the lines and each line is provided with a line-relay controlling a subsidiary signal at the central office, responsive to the flow of current in the line, which is determined by the telephone-switch at the substation. The

central source of current and the line-relay- The apparatus of my invention is intended signal-lamps c d and resistances 0 d more particularly for application to the operators plug-circuit, as shown in the diagram. The plug-circuit, generally considered, is of the usual type for systems of the character described, and consists of an answering-plug c and a calling-plug cl, the tip and ring contacts of each plug being united with the corresponding contacts of its mate by link conductors 1 2 of the plug-circuit, with arepeating-coil interposed in said link conductors and a central battery gin a bridge of said link conductors between the windings of the repeating-coil. A supervisory relay-magnet c is associated with the answering-plug and connected in the circuit of the conductor 2 between the central battery g and said answeringplug, and similarly a supervisory relay-magnet f. is included in the portion of conductor 2 leading from the battery to the calling-plug d. One pole ofthe battery g is grounded, and the third contacts of the plugs c and d, which are adapted to engage the testrings of the jacks, are connected with the free pole of said battery by conductors 3 4, respectively, which include the subsidiary The conductor 2 of the plug-circuit between the battery 9 and the calling-plug is in the normal or idle position of the plugs interrupted at the contacts of a relay h, the end leading to the ring-contact of the plug being connected to the armature h of said relay and theother end leading to the battery being connected to the front contact of said armature. The relay h has two windings. One of said windings h is included in a shunt 5 about the signal-lamp d, which shunt includes and is controlled by the armature and front contact of the supervisory relayf, and the other winding k is included in a conductor 6, which is connected in parallel or shunt with the resistance 61 and includes and is controlled by the armature h and its front contact of the relay hitself. The conductor 2, leading to the calling-plug, is normally connected by way of the back contact of relayarmature h and a conductor 7, including certain other apparatus, presently to be described, with the contact-plate t" of a continuously-rotating commutator or interrupter 't'. The contact-plate i takes up half the periphery of the commutator and the other half is of insulating material. Two contact-brushes t i bear upon opposite sides of the commutator, one of said brushes being connected to a grounded battery and the other being connected to a grounded generator of ringingcurrent 7c. The conductor 7 includes the winding ofa magnet Z, which controls a stepby step mechanism, hereinafter to be described, and includes and is controlled by a switch-lever m and its front contact, said lever being operated by the step-by-step mechanism aforesaid. A cam m is mounted upon a rotatable shaft u, said cam being circular except for two projections or lugs m m at diametrically opposite points upon its periphery. Theswitch-leverm andasimilarswitch lever m rest upon opposite sides of the pe riphery of the cam m, the ends of said levers being diametrically opposite one another and being yieldingly held down to the surface of the cam by springs. The switch-lever m normally rests against its contact-point,which is connected to the interrupter or commutator 't', and is separated from said contact-point when the switch-lever rides up upon one of the lugs m of the cam. The other switch=v lever m has a contact-point from which it is normally separated, but with which it ongages when moved by one of the lugs m of the'cam. This contact-point is connected to the limb Zof the plug-circuit between the battery g and the calling-plug, and the lever m is connected to a grounded source 8 of specialized current, such as a phonograph-transmitter or an interrupter which will produce a distinctive hum or tone.

The shaft or, which carries the cam m, is mounted to rotate in bearings and carries a ratchet-wheel 0. A spiral spring a, encircling the shaft, tends tokeep the same in the position illustratedthat is, with the lugs m m abutting against the ends of the levers m m Two pawls pp engage the ratchet-wheel 0 upon opposite sides. One of these pawls p is attached to the armature Z of the electromagnet l and is adapted to be pressed against the ratchet-wheel 0 by a spring g carried by the armature q of an electromagnet q. hen the magnet Z attracts its armature, the ratchet-wheel will therefore be rotated one step. The other pawl 19 is carried by a fiat-spring extension of another armature q ot' the magnet q and is adapted merely to hold the ratchet-wheel in the positions to which it may be advanced by the other pawl worked by the magnet I. When the magnet q is denergized, its armatures fall back, thus removing the pawls p 19 from engagement with the ratchet, whereupon the shaft n being released is rotated back to its original position. The magnet q isincluded in a shunt 8 about the supervisory lamp 0 of the answering-plug and is controlled by the armature of the supervisory relay e, which is responsive to the flow of current in the callingline. The armature q of relay q and aback contact for said armature control a shuntpath 9 about the armature 7L and its front contactin other words, the contacts controlled by armatures h and g are in multiple, and the closure of either completes the circuit through the retaining-winding 72/3 of magnet h.

The operation of the system is as follows: Assuming that a call has been transmitted from substation A in the usual manner and answered by the operator inserting her plug in the spring-jack, connecting her telephone in circuit and ascertaining the number of the subscriber wanted, after making the usual busy test the operator simply inserts the calling-plug d in the springjack of the line with which connection is desired. This is all the work that is required of her until the signal is made to take down the connection. When the calling-plug isinserted, the called-partys telephone being on its hook, thesupervisory relayfisinert. Consequently magnet h is also inert, and the ring of the calling-plug is thus connected, by wayof armature h and its back-contact winding of magnet Z and switch-lever m and its normal resting-contact, with the contact-segment 'i of the commutator or interrupter 2'. As the commutator rotates ringing-current is intermittently applied to the line, a steady current being substituted for the ringing-cu rrent during the intermissions. The magnet Z is responsive to the alternating ringing-current; but the magnet of the supervisory relay f is not. The telephone-receiver being on the hook at the called station, no return-path is provided for the steady current, so that neither of the magnets just mentioned is affected by such current until the subscriber has answered the call by removing his telephone from thehook,andso closing thecircuit. At each application of ringing-current to the line by the commutator i, therefore, the magnet Z will be excited and will attract its armature, and in the intermissions the magnet becomes inert and allows its armature to fall back. The magnet g at this time is excited, because the shunt-circuit controlled by the supervisoryrelayeof the calling-lineis closed, (the calling-subscribe1"s telephone being off the hook,) so that the pawls p p are yieldingly held against the ratchet-wheel 0. Each time the magnet Z draws up its armature, therefore, the shaft 91 will be held by the pawl 13 in the position to which it is advanced. 1f the called subscriber does not respond, the commutator will continue to apply the ringing-current intermittently to his line until the step-by-step mechanism has advanced the cam 'm sufficiently to engage the lugs m m with the switch-levers m m As the switchlever m rides up on one of the lugs m of the cam it breaks the circuit of conductor 7, leading to the commutator and the sources of current connected therewith,and simultaneously the switch-lever m is pushed into engagement with its outer contact. The effect, therefore, is to stop the application of ringing-current to the called line and to connect the source' of peculiar or specialized current- 5 with the conductorl of the plug-circuit. Current from the source 8 thus flows to ground through a winding of the repeating coil, whereby a corresponding current is induced in the other windings of the repeating-coil, which flows back to the calling-station and produces an audible signal in the telephone of the subscriber who is listening for a response to his call. This signal may be either spoken words from a phonograph or a hum or tone or any other audible .signal which the calling subscriber will recognize as meaning that no response is had from the called station. The

calling party upon hearing the special dontanswer signal knows that it will be of no use to signal the called party any longer and replaces his telephone on its hook, thus bringing about the illumination of his supervisory lamp 0 Since the supervisory lamp d of the called party is still lighted, the illumination of both lamps constitutes a signal to the operator to disconnect. At the same time the magnet q is deprived of current by the opening of the shunt S and allows its armature to fall back, thus releasingthe ratchetwheel 0. The shaft n is therefore returned to its initial position by the coiled spring at. The armature q in falling back closes the circuit through the winding 72 0f magnet h,which in drawing up its armatures permanently cuts off the ringing-current from the called line. In ordinary cases, however, the called subscriber will answer and in taking his telephone for use will close a bridge of his linecircuit, whereupon the supervisory relay f at the central office will respond to the flow of current in the line and close the shunt 5, which includes the winding 7L2 of magnet h. This magnet in drawing up its armatures cuts off the ringing-current and establishes the talking-circuit through the repeating-coil. Circuit through the retaining-winding 71 15 also closed by armature 72%, so that the magnet h is now independent of the telephone-switch at the called station and maintains the ordinary talking-circuit connections as long as the plug remains in the springjack.

It will be apparent that my invention is capable of being applied to the receiving end of a trunk-line to signal back to the answering board, and where in the claims I use the term calling-line I do not mean to restrict myself to a subscribers line. In fact, my invention is capable of application to telephone systems of various kinds, and the arrangement shown in the drawings may be modified within comparatively wide limits and still make use of the new ideas which I have herein set forth. I do not therefore wish to be understood as limiting myself to the precise apparatus and circuits illustrated; but,

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

1. The combination with a calling and a called telephone-line and means at a central office for uniting them, of an automatic ringing device at the central office for sending signaling-current over the called line, a source of distinctive signaling-current, a switch for connecting the same with the calling-line, a time device set in operation simultaneously with the automatic ringing device, and means controlled by said time device for actuating said switch, whereby the calling party is antomatically notified when the called station has been signaled a given time, substantially as set forth.

2. The combination with a calling and a called telephone-line and means at a central I &

office for uniting them, of an automatic ringing device at the central office for signaling the called station, a source of peculiar-or characteristic signaling-current, a switch for disconnectingthe ringing-current from thecalled line and applying the peculiar signaling-current to the calling-line, and an electrical device operated by the flow of ringing-current in the called line, for bringing about the operation of said switch, whereby ringing-current is automatically applied to the called line for a given time and then stopped, and a signal transmitted to the calling-station, substantially as set forth.

3. The combination with a calling and a called line, and means at a central office for uniting them, of a source of ringing-current and a ringing device at the central office for connecting the same with the called line, means controlled through the agency of a switch at the called station for disconnecting the ringing-currenl, a time device set in operation when ringing-current is applied to the called line, a source of characteristic signaling-current and a switch for connecting the same with the calling-line, controlled by said time device, whereby the called party is automatically signaled for a definite time and, upon his failure to respond, a report to that elfect automatically made to the calling party, substantially as set forth.

4. The combination with a telephone-line extending to a central office, and means for there connecting it with a second or called line, of a source of ringingcurrent and means for connecting the same with the called line to signal the called party, means at the central office, under the electrical control of the called party for disconnecting the signalingcurrent'from the line, a source of characteristic signaling-current, and a switch for applying the same to the first-mentioned or calling line, and a time device for operating said switch, said time device being controlled by the flow of ringing-current in the called line, substantially as set forth.

5. The combination with a calling and a called telephone-line, and means at a central office for uniting them, of a source of ring ing-current and means for automatically applying the same to the called line, means at the central office, under the electrical control of a switch at the called station, for disconnecting the ,source of ringing-current, a

source of peculiar or characteristic signalingcurrent, and an automatic switch for applying the same to the calling-line, an automatic interrupter for intermittently disconnecting the ringing-current from the called line, and a step-by-step device operated by the intermittent flow of ringing-current, controlling said automatic switch, whereby the called party is automatically signaled for a given time, and a signal then transmitted to the calling party indicating that there has been no response, substantially as set forth.

6. The combination with a calling and a called telephone-line and means at a central office for uniting them, of a source of ringing-current and an automatic ringing device for applying the same to the called line, means controlled through the agency of a switch at the called station for disconnecting, the source of ringing-current, a source of current connected with the calling-line,means at the substation of the calling-line for de termining the flow of current therein, and electromagnetic mechanism controlled by the flow of current in the calling-line, for disconnecting the ringing-current from the called line, substantially as set forth.

'7. The combination with a calling and a called telephone-line and means at a central office for uniting them, of a source of ringing-current and means for automatically applying the same to the called line, means at the central office under the electrical control of a switch at the called station, for stopping the flow of the ringingcurrent, a source of peculiar or characteristic signaling-current, a switch for applying the same to the calling-line and disconnecting the ringingcurrent from the called line, an instrument in the calling-line responsive to such peculiar signaling-current, a rotatable cam for actuating the switch last mentioned, a device for V intermittently interrupting the flow of ringing-current in the called line, and an electromagnetic step-by-step device responsive to the intermittently-interrupted ringing-current, for controlling the rotation of the aforesaid cam, substantially as set forth.

In witness whereof I hereunto subscribemy name this 4th day of December, A. D.'1900.

JAMES L. MCQUARRIE. \Vitnesses:

ELLA EDLER, ADELL HOCKETT.

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