US1282966A - Telephone system. - Google Patents

Description

F. Nl. SLOUGH.

TELEPHONE SYSTEM.

APPLICATION FILED 1AN.3|. |916,

Patented oet. 29, 1918,

- FRANK M. SLQUGH, 0F ELYRIA, OHIO, ASSIGNOR, BY MESNE ASSIGNMENTS, TO STROMBERG-CARLSON TELEPHONE MFG. CO., OF ROCHESTER, NEW YORK, A

CORPORATION or NEW YORK.

d TELEPHONE SYSTEM.

nasaece;

Specication of Letters Patent.

Patented Uct. 229, Mlle.

Original application filed November 12, 1914, Serial No. 871,666. Divided and this application filed January 31,1916. Serial No. 75.222.

To all Itti/0m t may concern:

-Be it known that I, `FRANK SLOUGH, a citizen of the United States, residing at Elyria, in the county of Lorain and State of Ohio, have invented certain new and useful improvement-s in Telephone Systems; and l do hereby declare the followingto be a full, clear, and exact description of thein vention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to improvements in telephone systems, and especially to iinproveineiits in what are known as automatic ringing, systems, in which mea-ns `are provided for continuing' the ringing of the subscriber, after itlias once been started by the operator, until the subscriber responds, ivlien it is automatically disconnected through agencies under the con-trol of the subscriber. In systems of this kind heretofore in use, so far as I ain aware, the disconnect apparatus hasbeen made suchthat it would re spend to the substation signal operating` current it the conditions happened to be right. For example. in the strength of current systems which are those almost universally in use, so far as I ain aware, the disconnect apparatus has been operated by increasing` the tovv of' current in the line, for example, by substituting a low resistance talliiigset for Vthe high resistance bell bridge, and thereby increasing' the strength of the current, so

that the disconnect device would operate,. whereas, it had refused to respondto the strength of current flowing` before the low resistance bridge was placed upon the line. lf, however, `connection were inadeto a line upon which were a number `of su'bstations, the impedance offered to the flow of alterhating` current or signal operating current would be so reduced according; to a Well known law of electricity, that the flow of current would noiv be sufficient to operate the disconnect device just as elfectivelyas if the subscriber had responded. Therefore, the first impulse of ringing current `would i'lisconnect the ringing `current andthe desired subscriber Would neverbe rung.

ltreonently, alsol` the conditions of a line are such that less current willflow over the same when the receiver is off the hook Vthan will iioiv over a short line when the reerable limitation has been placed upon the use of the saine, and the operating coinpanics employing the same have been handicapped, especially where long' country lines and short city lines center in the saine ,en

change. This trouble has also been keenlyv felt Where multi-party lines have been cm- Vployed, and as these conditions of long and short lines, some` of which are multi-party lines, are employed in practically all enA changes, the automatic ringing hitherto used has had its limitations.

Efforts have also been made, so l am informed, to cure vthese defects, one of which has been the employment cfa" specially coustructed relay in the ringing circuit. @ne of the forms which has been employedfor this purpose was constructed ivitha copper band around a portion of the core, the copper band being provided `as a sort of closed secondary transformer Winding for the purpose of dissipating the alternating` current pulsations, the idea beingto cause the rela v to be insensitive to alternating current tloiv. at the saine tiinebeing sensitive to direct current flow. Such expediente have failed largely because of the fact that such a relay is composed in part of a normally open ina netic circuit, and is, therefore, inefficient as ai transformer, particularly to alternating currents of commercial frequencies used for the purpose of ringing telephone bells. Therefor, only a portion of the alternating` current pulsations Would be subdued by the 'copper band, the balance being; sometimes` suicient to cause the ope ation of therelay. Sucli systems have. been subject to the same defects heretofore described, in that sible to exclude all of the ringing` current' and at the same time enable the subscriber at all times to control the cut-oli device, and il:`

the system 'was so constructed that little or none of the ringing` current, passed through the cut-oll` control arrangement, the conditions would be such that for certain lines insuliicient current could pass through to cause its operation. In fact, all oli' the automatic ringing systems hitherto in use, so far as I am aware, have been quite marginal in one respect or another, and conditions have been such that i'or certain lines they would open ate improperly, and as such lines are always met with in practice., sooner or later, these systems have been detective.

Needless to say, numerous other eli'orts have been made to improve the system so as to make it meet all the conditions of practice, but so far as I am aware, this has not been done.

The object of my invention is to overcome these obstacles and toproduce a cut-ott device Which vill under no circumstances respend tothe ringing current at all until the subscriber has responded. In aeconr plishing` these, I wipe out all oit the delicate adjustments, strength of current, marginal Schemes, mechanisms for preventing the cutoii controlling apparatus from responding to fluctuating; currents and other such delicatemechanisms, and provide a cutbll controlling mechanism which responds to the alternating current or not. My success lies in providing a cut-off mechanism which will not respond, even though its controlling mechanism is responsive to fluctuating currents. I further provide means controlled by the subscriber1 for causingthe operation of the cut-oii mechanism and a cut-oil." mechanism which will notl respond until the subscriber starts the same into operation.

@ther objects of my invention and the invention itself Will probably be better understood from a description of particular embodiments.

This application is a division of my application #871,666, filed November 1914i. Figure l is an illustration of the preferred embodiment of my invention.

Fig. 2 is a diagrammatic illustration ot' electric current and magnetic ilus; Waves.

Referring non7 to the embodiment illustrated in Fig. l, at I is shown a telephone line which may be here spoken of properly as thc calling line, and which I have ior convenience shown as a single partyelii'ic. At II` is shown a. second telephone line, shown lor convenience as a multieparty line, and which may be properly called a called line. At III is shown a main station. Each telephone line is provided With substation apparatus, shown on the line ^I n and which includes a signal bell B, a receiver l, a transmitter D and a switch-hook E. A condenser 6 may be included in the bell bridge 7. The line I is connected by line conductors 8 and 9 to the main station. The line II is provided With a plurality of substations, A1, A2, A3, A4. VEach is provided with bells B1, Bg, B3, 13 which are included in the telephone apparatus. This apparatus also includes receivers C1, C2, C3, C4, transmitters D1, D2, DE, D and switch hooks El, E2, E3, E4. Condensers may likewise be connected in the bell bridges.

I have illust ated a third telephone line,

shown at IV, which may also be called a called line. This line is provided with substation apparatus A5 which includes a. bell B5, a receiver C5, a transmitter D5 and switclrhoolc E5. The line II leads by its line limbs or conductors 1G and l1 to the main station and the line IV leads by its line limbs or conductors 13 and 14 to the main station. At the main station means are provided for connecting the telephone lines together, here shown as a cord circuit, `which consists of a plurality of strands in cluding talking strands l5 and 16. Switching apparatus is provided for connecting the cord circuit to the telephone lines, here shown as plugs and jacks, the line I beingv provided with a jackl, the line II vwith jacks J, and J2 and the line IV withV jacks J and Ji. The cord is provided with a n answering plug I and a calling plug Ill. l? course the lines may be provided with any suitable number of jacks. Each line is also provided with line signals, the line I With thcline signal L1, the line II with the line signal L2 and the. line IV with the line signal L4. Each line is also provided with line relays, the line I with the line relay Gil, the line II with the line relay G2 and the line IV with the line relay Gp Each line is also provided with cut-oli0 relays, the lines I, II and IV being provided with the cut-oli' relays H1, H2 and IL, respectively. The cord circuit is provided With suitable supervisory signaling appad ratus, the answering end of the cord being provided with a supervisory lamp L and the calling end of the cord being provided with a supervisory lamp LG. These lamps are controlled by supervifscry relays K, Kl for the lamp L Vand Iig and IL, 'l'or the lamp L6.

IIO

Means are provided for operating the Signal tens B, B1, B2, B3, B B5. in the Vform shown these means are located at the scriber is connected, but one generator is necessary. In this vwell known harmonic system each generator is adapted to produce an alternating current of a certain definite frequency and the bells at the substations respond one to each of these frequencies. This arrangement, however, may be employed without departing from the spirit of my invention.` Means are provided for connecting one of the generators to the bell of the desired subscriber, in order that the bell may be operated by the current supplied by the generator. In the form shown, this connection is effected through conductors, switches, a portion of the cord circuit, the apparatus for connecting the cord to the lines and the telephone line. In the form shown I provide means for breaking up the ringing current into intervals, so that the subscribers bell may be rung at intervals, avoiding an incessant ringing of the bell. These means are shown as commutatore N,

N1, N2, N3 which rotate constantly alternately making and breaking the circuit of the ringing circuit. At O, O1, shown switches, here illustrated as manual switches controlling the connection of the generating means to the signal bell, one key being provided for e-ach generator.

At Q, Q1, Q2 and Q3 I show relays which are controlled by the keys O, 01,02, O3,

which in turn control the connection of the generators to the lines. At Ris shown a relay which controls the talking strands of the cord circuit and the connection of the ringing current to the telephone line. At S is shown a relay which controls the disconnection of the ringing current from the telephone line. This relay also controls the circuits of the relays Q, Q1, Q2 and Q3. While the ringing is in progress, ringing current flows through the relay S, but the current produced by the generating means is of such a character that the armature of the relay S fluctuates without closing the switch -21 for any appreciable length of time, so that the connection `between the ringing generator and the bell will not be interrupted. When, however, the character of the current flowing through the relay S is so changed that the magnet luX is constant or substantially unidirectional, the

O2, O3 are switch 20`-2l is closed and whichever one of the relays Q, Q1, Q2 or Q3 has been operated, will be denergized and the connection between the ringing generator and the bell interrupted. The character of the current which flows through the relay S may be changed in a number of ways and the character of the flux in the relay S may be changed in a number of ways to effect the functions which it is to perform. In thc form shown I have accomplished this change by superposing upon the alternating current produced by the generator a directw current, which, upon the response of the called subscriber, will cause a result-ant current of a dierent character. In the embodiment illustrated in Fig. l the wave form will be .changed with respect to the line of zero polarity. llhile lthe unmodified alternating current was flowing, the flux in the circuit of the relay S would be of alternating polarity, following the alternating current.

However, when the current is shifted, its flux will be substantially constant, or of substantially uni-directional polarity, and the magnet will be operated for a sutlieient length of time to cause the disconnection. However, when the alternating current alone is applied, the switch 20-21 will be closed for such brief intervals of time that the magnet Q will never let go its contacts.

The operation of the system illustrated in Fig. l as follows: Assuming that the sulscriber at A desires to communicate with the subscriber at A5, the receiver C is removed from the switch-hook E. closing the switch Ilk) and completing a circuit through the` line relay G1, causing' the illumination oi the line lamp L1. This lamp is located sn that it will attract the attention of the operator, who will insert the plug P into the "ack J and in the well known manner learn that it is the subscriber at A that is wanted. She then inserts the plug l), into one of the `jacks J, and deprcsses one of the ringing keys, according to what character of current is desired. Assuming that the generator .ll/l produces the character of current desired. the key 0 would be depressed, completing a circuit as follows: ground at QS-contact 24-Orelay Q-conductor 25-relay R- conductor 26-27-2S-29-30-312w33 S4- battery 35-to ground at 3G, energizing the relays Q and R, the relay K having previously been energized in the well known way when t-he plug P was inserted into the jack H through a circuit. including the answering end of the cord and the calling line. and atl, completing a locking circuit for the relay Q through LO Y i2 to ground at 4&3. The attraction of the armature Ll1 closes a switch iL-eli in the ringing circuit. The relay R attracts its armatures l5 and 46, in-

terrupting the talking strands of the cord The relay Q will attract its armatures circuit and closing the switches t5-47 and i6-i8 in the ringing cir-cuit. The ringing circuit vvillxnoiv be traced as follows: from ground Jew-through Mconductor Ocon mutator N-conductor T-TJfJr-tl-relay S -Q-fllT-et-tip i3-tip spring .5t-conductor li-the bell Il conductor 13 lea'f spring -sleeve 5(5-iG-,`LS-batteiy G0-` to ground (Si. Thus current Vtlowiiig through the relay S will rapidly energize and denergize the saine in such a manner that the switch 20-21 will be closed, if at all,ronly for short intervals of time. The periods for which this switch will be closed, ii at all, will be functional to the frequency or' and in harmony with the ringing current employed. The intervals of closure of this switch during the ringing period will be soslight that the shunting effect of the magnet Q will be ineffective to denergize the relay Q, owing to the fact that the magnetism in a short-circuited relay decays very sloivly. All during the ringing period, the condenser 62 at sub- Vstation A5 preventsthe flow o't direct current from the battery 60.

Vhen the subscriber responds, the switch Fir-G3 will be closed, oiving to the removal of the receiver C5 from the hook E5, which maybe spring pressed upward. V This vvill shunt the condenser 62 and admit the lovv ot' direct current from the source 60. As a rcsult, a different kind ot current will flow in the circuit, including a relay'S, and as a result thereof the relay S will operate. In the #form shown the current ioiving in the cir Acuit of the relay S, atterthe receiver is removed from the hook, will be an alternating current, which is shifted with respect to the zero abscissa, or it may be a pulsating current, according to the relative strength of the alternating` and direct currents. This current will cause a substantially constant, or substantially unidirectional, flux to tlovv in the magnet S. The magnet of the relay S will now be energized for a sufficient length of time to hold steadily closed the sivitch Z0-2l long enough to effectively shunt the magnet Q which Will be denergized, Where upon the armature 41 drops back, opening the ringing circuit at 41-44: and disconnecting the generator from thesignal bell. At the saine time, the circuit of the relay t will be broken, still further interrupting the ringing circuit and restoring the cord circuit; The subscribers Will then be in connection and at the termination of the conversation, the operator will be apprised of the desire for the disconnect, and the plugs will be Withdrawn, restoring the system vto normal.A

In Fig. 2 I have shown diagrammatieally one theory upon which my apparatus may be operated. `The curve X represents the flow ot' alternating current during the ringing period. The curve Y represents the direct current introduced :into the circuit when the receiver is taken from the hook. The curve Z representsthe polarized alternating current inthe ringing circuit When both the ringing machine and the source are connected to the ringing current. VThe curve IV represents tlieiiux in the relay S when both the ringing machine and the direct current are connectedin the circuit.

. I have shown the `theoretical diagram illustrated in F 2 as being a mere theory as toivliat might take place under a given set of conditions, but I do not Wish to be limited either to the embodiment illustrated in Fig. 1 or to the theory of operation Which I have illustrated in Fig. In fact, .I have illustrated `this embodiment and thisA theoretical diagram in order to better explain `my invention, and not, that I `may kbe limited thereto, as it -ivill be apparent that many i departures may be made from the modifications and the theory illustrated, especially *when the claims are consulted.

vand means controlled bythe substation apparatus tocause said second relay to close the contacts in the circuit ofthe iirst named relay tor an appreciable length `of time,

whereby said relay is operated to interrupt the ringing circuit. Y y

2. In a telephonev syst-ein, thej combination oi Va signalY device, a source or" current, a ringing circuit including said source and saidsignal device, a relay controlling said `ringing circuit, a circuit for said relay, a

shunt et said relay and a second relay in the ringing circuit controlling said shunt,

a shunt ot the second relay and a non-iiiductive resistance in said shunt and substation apparatus associated with the signal device controlling said second relay.

3. In a telephone system, the combination of a main station, a telephone line leading to the main station, substation apparatus on the line including a signal bell and a switch, means at the main station for generating current to operate the bell, a ringing circuit including said bell and said generating means, a relay for the ringing circuitcontrolling the same, a second relay in the ringing circuit governingV said firstnained relay, i a. shunt `oi thev second relay and a non-inductive resistance in said shunt and means including the switch at the substation controlling the slo7 acting relay.

4. In a telephone system, the combination of a signal device, a source of alternating ringing current, a ringing circuit including said source and signal device, a relay oontrolling said ringing circuit, a oil-Cuit for said relay, a shunt of said relay, a second relay responsive to a flow of polarized ourrent to Control said shunt to shunt said rstnamed relay, said second relay being irresponsive to alternating currents to cause the operation or' the first relay, a shunt of the second relay and a non-inductive resistance in said shunt and substation apparatus associated with the signal device adapted to cause a flow of polarized current through said second relay to operate the second relay.

In witness whereof I have signed my name hereunto this 22nd day of January,

FRANK M. SLOUGH.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C.

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