US563073A - Charles e - Google Patents

Description

(iNo Model.)

C. E. SCRIBNER.A

APPARATUS POR TELEPHONE SWITGHBOARDS.

No. 563,073. Y Patented Jun 30, 1896.

UNITED STATES PATENT OFFICE.

CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR T0 Tl-IE IVESTERN ELECTRIC COMPANY, OF SAME PLACE.

APPARATUS FOR TELEPHONE-SWITCHBOARDS.

SPECIFICATION forming part of Letters Patent N0. 563,073, dated June 30, 1896.

Application led .Tune l2, 1895. Serial No. 552,525. (No model.)

To all whom t may concern,.- connection is made with the line and substi- Be it known that I, CHARLES E. SCRIBNER, tuting for it a supervisory signal-lampassoa citizen of the United States, residing at Chiciated with the connecting-plu g, and for causcago, in the county of Cook and State of Illiing the illumination of the latter signal-lamp 55 5 nois, have invented acertain new and useful When the telephone is replaced upon its Improvement in Apparatus for Telephoneswitch-hook at the substation. Switchboards, (Case No. 384,) of which the Each telephone-line is controlled at its subfolloiving is a full, clear7 concise, and exact station by a switch operated automatically description, reference being had to the acin the use of the telephone,whichis arranged 6o 1o companying drawing, forming a part of this to ,close the line-circuit While the telephone specification. is in use, but to interrupt this connection, or

My invention relates to the automatic opt0 close it through a path of very high reeration of signals of telephone-lines termisistance, when the telephone is idle. At the nating in a telephone-switchboard. Its obcentral station I lead from one conductor of 65 15 ject is, in general, to provide for the switchthe line-circuit a ground branch through an board-operator a simple and efficient system impedance-coil and the line-signal lamp, inof signals adapted to indicate continuously cluding a signaling-battery which may be the condition of each telephone-line, Vor of common to different lines of the exchange. the different members of a pair of connected When the switch at the substation is oper- 7o 2o lines. ated in the use of the telephone, the line-sig- Prior to my invention annunciators or visinal is illuminated and indicates the call or ble signals have been included in telephoneinitial signal to the attendant. lines, together With sources of signaling-cur- Each terminal plug is provided with a closed rent, the telephone-lines being provided with circuit through one helix of an induction-coil, 7 5 2 5 switches at their substations adapted to open the other helix of the same coil being included and close the line-circuit, and thus to disin the circuit of the other terminal plug ot play or render inert the signaling instruthe pair, and from the central point of each ments at the central station when the telehelixa conductor is led through asupervisory phone is in use or is idle. When such lines lamp-signal to the free pole of the same sig- 8o 3o were connected together by means of loopnaling-battery. Thesehelices are constructed conductors in the switchboard, it has been of such low resistance that When a plug is infurther customary to place in connection serted into a spring-jack the line-signal lamp, With severed portions of the link conductors being shunted by the induction-coil helix of other visible signals associated with the terlow resistance, is extinguished; In a shunt 8 5 minal plugs of the plug-circuit, designed to about the supervisory signal is connected a enable the operator to supervise the connecresistance-coil, together with a' battery or tion during its continuance by indicating the other source of current of such polarity and condition of the telephonie appliances at both strength that the current from the common stations of the united-circuits. signaling-battery, in the closed line-circuit, 9o 4o In a prior application, iiled April 16, 1895, is diverted from the signal-lamp, or, in other Serial No. 545,855, I have disclosed a mode Words, the battery in circuit about the superof using small incandescent lamps as such visory signal coperates with the main sigvisible signals in telephone circuits. naling-battery to produce a condition of no My present invention aims to employ such dierence of potential between the terminals 95 45 signal-lamps, placed in direct connection of the lamp. Under this condition, when the with the telephone-line, for indicating the circuit at the substation is again interrupted, various signals required; and to this end it this balanced relation is destroyed and curcomprises means for exciting a line-signal rent is created through the supervisory sigpermanently associated with the line, when nal to cause its illumination. The operation roo 5o the telephone is removed from the switchof this system of signaling is then as folliook forextinguishing this signal-lamp when lows: When the telephone at the substation is removed from its switch-hook, to transmit an initial or call signal, the line-lamp is illuminated. When the operator makes connection with the line, this lamp is extinguished. Then the telephone is returned to its idle position, the supervisory signal is illuniinated. Since both members of the pair of plugs used in uniting two lines are provided with such supervisory signals, these signals constantly indicate to the attendant the condition of the substation apparatus at both stations. The operator may be instructed to remove the connection only when both supervisory signals have become lighted.

For the purpose of rendering the lamp-signals as sensitive as possible to current in the line-circuit, I prefer to employ a device described in a pending application led April I6, 1895, Serial No. 545,856, which consists in a shunt-circuit including a source of current about the signal-lamp, the current in this circuit being so adjusted with relation to the lamp as to be barely insufiicient to illuminate the lamp. A very slight addition to this current, by an independent current created in the complete signaling-circuit, is suiiicient to cause the full illumination of the lamp, and thus to display the signal.

My invention is adapted for use in exchange systems in which the substation-transmitters are supplied with current from a common source located at the central station. I have illustrated it in connection with such a system in the accompanying drawing.

In the drawing two substations are represented connected byline conductors with the apparatus of a telephone-switchboard at a central station. The appliances at the substations are of the usual character. They comprise a receiving-telephone a, a transmitting-telephone d', a signal-bell a2, and an automatically operated switch a3, acting to switch the telephone and the bell alternately in to connection with the line. The bell a2 should have a high resistance, compared to that of the telephonewas iive thousand ohmsfor the purpose of practically interrupting the line-circuit when the telephone branch is l interrupted. Two substations thus equipped,

B and C, are shown in the drawing. Station B is connected by line conductors l and 2 with apparatus in a switchboard at the central stat-ion D, the different line conductors terminating in the corresponding contactpieces of a spring-jack e in the switchboard. The line conductor l is continued through an inductive resistance or impedance coil f, and through the line-signal lamp g to one pole of a battery or other source ot current lL, which is common to the different lines of the exchange. The other line conductor 2 is continued through a similar impedance-coil 1l to the other pole of the same battery h. The impedance-.coils fand@l should be of about one hundred ohms resistance each. A conductor 3, including a resistance-coil k, is connected in shunt of the signal-lamp g, and includes in its circuit a battery or other source of current 7i', which also is common to the different lines. The strength of battery 71. and the resistance of coil la are so adjusted that sufficient current fiows through lamp g to raise it almost to the point of illumination.

The usual pairs of connecting-plugs Z and Z are provided for the operator to enable her to establish connection between different spring-jacks for the purpose of looping lines into circuit with each other. The like contact-pieces of these loop-plugs are connected together, the tips m being united through a conductor 4, and the sleeves or tubes through another conductor 5. The switch springs and the normal resting-contacts of a callingkey 1L are included in these conductors, the key being adapted, when operated, to disconnect the plug Z from its mate and to close its terminals to the poles of a generator o, suitable for operating the substation-bells a2. A listenin g-key p also has its springs connected with the conductors 4 and 5, its oilice being to bridge the operators telephone-set q across the plug-circuit 4 5 when the key is depressed.

The conductor 5 includes in series two helices r and r2 of a transformer or inductioncoil 7'. From the point of junction of these two helices a conductor 6 is led to that pole of the battery 7L which is connected with line conductors 2. The conductor 4 of the plugcircuit likewise includes in series two helices r3 r4 of the same induction-coil. These helices are united through two signal-lamps s and s. These lamps are associated, respectively, with the terminal plugs l and Z of theplug-circuit, and should for convenience be placed close together in the switchboard.

The point of junction of lamps s and s is connected with a battery t, whose other terminal is connected through a conductor 7 with that pole of battery h in which t-he line conductors l terminate. A shunt-circuit is provided about each of the lamps s and s', as about the line-lamps. This shunt consists in a resistance-coil, connected from one terminal of the lamp to the conductor 7, the resistance-coils about lamps s and s being designated u and u', respectively. The lamp s is thus in a closed circuit formed by the resistance-coil u and battery i. The lamp s is in a similar circuit with the battery t and its coil u. The direction and strength of battcryzf in each of these circuits should be so adjusted with relation to the resistance-coil that while the plug-circuit is open or disconnected a sufficient current will traverse each of the lamps s and s to fully illuminate them; but its strength should also be so adjusted with relation to battery h that when the conductors 4 and 5 of the plug-circuit are connected with the conductors l and 2 of the line-circuit, the latter being connected together through a low-resistance path at the substation, sufficient current from battery t will be diverted from its path through lamp-signals IOO IIO

S and s' to leave these unilluminated. This adjustment will be referred to later in connection with the operation of the complete system.

It may be sufficient here to state that good results may be obtained with a battery h of forty volts electromotive force, and a battery t of six volts, the resistance of coils u and u' being approximately fifteen ohms, and that of the substation-telephone being about one hundred ohms. Like poles of batteries 7L and tshould be connected with conductor 7. The helices of induction-coil r should be of moderately-low resistance-for example, of about twenty-ve ohms each.

ln order to trace the operation of this system, assume that subscriber at station B requires a connection with station C. The subscriber at the former station, by removing his receiving-telephone a from his switch-hook, permits the latter to connect the line conductors through the low-resistance telephoneset. The battery h now finds circuit through the line conductors l and 2 and this low-resistance branch at the substation. This current is ot course divided in the switchboard between conductors l and 3, the greater part, however, traversing conductor l and the lamp-signal g. A sufficient current is thus caused to flow through this signal-lamp, in addition to that normally iiowing from battery h', to illuminate the lamp and thus to indicate to the attendant the subscribers initial signal. The operator then inserts plugZ into spring-jack e, and, by operating her listening-liey p, brings her telephone-set q into connection with the plug-circuit, and learns the order from the subscriber for the connection desired. By the insertion of this plug into spring-jack e, the helices r and r3 of induction-coil r are brought into shunt of the impedance-coil t', and the impedance-coilf and line-lamp g, respectively, so that the current produced by battery h through signallamp gis diverted from that path through the path of low resistance formed by conductor 7, lamp s, a coil u, and battery in parallel,

' helix r3 and conductor 4, returning through conductor 5, helix r', and wire 6.l The signal-lamp g is thus extinguished or returned to its normal inert condition.

It will be noted that during the idleness of the plug-circuit the batteryt creates in the circuit formed by resistance-coil u, lamp s,

- and its leads a current which fully illuminates the supervisory signal s. Vhen the plug is inserted in the spring-jack e, however, a portion of the current from battery 2f is diverted through the line-circuit; or, in other words, batteries 7L and t cooperate to produce a condition of no difference of potential between the terminals of the signal .3, practically the entire current created by the two batteries finding circuit through the resistancecoil u to the conductor 4 and thence to the telephone-line. The current from battery h nds circuit through conductor 7, from whose point of junction with the other circuits it has two paths, namely, one through battery t and each of the lamps s and s' to the portions 4 4 of the conductor of the plug circuit and thence to the corresponding lines, and the other through resistance-coils a and u to the same portions of the conductor of the plugcircuit. Considering the circuit to the callingline, for instance, the current has a path through a circuit of two branches, one including coil u and the other including lamp s and battery t. In the latter circuit the opposing electromotive force of battery t is so adjusted with relation to the resistance of coil u and the current which is passing through it from battery hV that the current tending to flow from battery h through the lamp s is exactly opposed; while as to the current which battery t tends to set up in the short closed circuit including coil u, lamp s, and battery that is opposed by the difference of potential between the terminals of coil fa, which is set up by the battery h. To be accurate, the electromotive force of battery t, the resistance of coil u, the resistance of the external circuit through the line, and the electro'motive force of battery h are so adjusted with relation to each other that no difference of potential exists between the terminals of the lamp. The supervisory signals is thus extinguished, and remains dark as long as this condition of balance is maintained by the continuity of the line-circuit at the substation.

Having learned the order, the operator establishes connection with the lines S 9 to station C by inserting plug Z' into spring-jack e of that line. She rings the substation-bell a2 at station C by operating the calling-key n in the usual way.

When the plug Z is inserted into the springjack e, no current is created by battery h through the plug Z', since the line-circuit at station C is as yet interrupted, or is at least closed only through the bell a2 of very high resistance. Hence supervisory signal s' is lighted. This condition remains until the subscriber at station C, responding to the signal of his bell, removes his telephone from its switch-hook and permits the latterv to close the lin e-circuit through the telephone. When this is done, current finds circuit from battery h, through conductor 7 and resistancecoil u, thence through conductor 4, plug l', to the line-circuit, returning through the corresponding conductors of the other side of the circuit. This current is in the proper direction and of the proper strength to bring about the condition of no difference of potential between the terminals of signal s', so that the latter also becomes dark. When both supervisory signals are thus obscured, it may be assumed that the subscribers are in conversation. If either telephone be replaced upon its switch-hook,the current in that line-circuit is interrupted and the corresponding supervisory signal is illuminated. When both signals become lighted, it may be assumed that IIO circuits and sources of current which con-.

stitutes my invention is not limited to use with lamp-signals, since any of several wellknown forms of visible signals might be substituted for the signal-lamps described. It is also possible to adaptthe same circuit arrangement to systems involving other modes of supplying current to the substation-transmitter without the exercise of invention.

I claim as new- 1. The combination with a signaling-circuit divided atV one point Yinto two parallel branches of fixed resistance, of means for varying the resistance of the signaling-circuit, a source of signaling-current in the-undivided portion of the Vsignaling-circuit, a signal-indicating instrument requiring for its operation a denite predetermined current in one oi' the branches, a separate source of current in one of the parallel branches, the polarivties of the source of signaling-current and of the said other source being oppositely directed Vin the portion of the circuit including the signaling instrument, the electro- -motive force of said last-mentioned source being sufficient to prevent current from-actuating the signal when thesignaling-circuit is closed;V whereby the closing of the signalingcircuit renders the signal inert, and the opening of the signaling-circuit causes its display, substantially as described.

2. The combination with a telephone-line provided with a switch adapted to interrupt the circuit and a source of current in the line, a portion of the line being divided into two parallel branches, of a signal-lamp in one of the branches, a resistance-coil in the other branch, and a source of current in one of the branches, the polarity of said last-mentioned source of current being adapted to oppose the passage of the signaling-current through the lamp and its electromotive force being suiiicient to prevent the illumination of the lamp by current in the signaling-circuit, substantially as described.

3. The combination with a telephone-line, of a branch thereof including a signal-lamp and a source of current, a spring-jack connected with the line, a plug-circuit for making connection with the spring-jack, and a conductor of low resistance connected with the plug adapted to form a bridge of the linecircuit including the said source of signalingcurrent, when connection is made with the line, whereby the signal-lamp is shunted.

4. The combination with a telephone-line, of a spring-j ack constituting a terminal thereof, a signal-lamp together with a source of signaling-current in a permanently-closed bridge of the line-circuit, a connecting-plug and its plug-circuit, and a conductor of low resistance including a signal-lamp connected with the plug adapted to be brought into a bridge of the line-circuit when the plug is inserted into the spring-jack, substantially as described.

5. The combination with a telephone-line, of a switch for interrupting the line at the substation, a spring-j ack constituting a terminal of the line in a switchboard, a signal-lamp, a low-resistance branch of the line-circuit including a source of signaling-current temvisory signal-lamp in said low-resistance" branch, a shunt-circuit including a resistancecoil about the lamp, and a source of current in the closed circuit formed by the shunt and the conductor including the lamp, the source of current being so adj usted with relation to the source of signaling-current as to produce a condition of no difference of potential between the terminals of the supervisory signal when the line-circuit is closed, substantially as described.

6. The combination with a telephone-line, of a switch at the substation for interrupting the line, a spring-jack for the line in aV switchboard, an impedance-coil, asignal-lamp, and a source of signaling-current in a permanently-closed bridge of the line-circuit, a pair of loop-connectin g plugs for uniting lines, the different contact-pieces of each plug being united through ahelix or helices of the same induction-coil and through a source of signaling-current, a supervisory lamp-signal in the conductor uniting the contact-pieces of each plug, a shunt including a resistance-coil about each supervisory signal-lamp, and a source of current in each shunt adapted to divert the current of said source of signalingcurrent from the corresponding supervisory signal When the line-circuit is closed, substantially as described.

7. The combination with a telephone-line having a switch for interrupting the line-circuit, a spring-jack for making connection with the line, of a plug in the spring-jack in continuation of the line, a source-of signalingcurrent in circuit with the plug, the circuit of the plug being divided at one point into two parallel branches, a signal-lamp in one of the branches, and a source of current in one of the branches, the said last-mentioned source of current being of such strength and polarity as to prevent the illumination of the signallamp by current from the signaling-battery, substantially as described.

In witness whereof I hereunto subscribe my name this 29th day of April, A. D. 1895.

CHARLES E. SORIBNER. lVitnesses:

ELLA EDLER, DUNCAN E. WILLETT.

porarily associated with the circuit, a super- IOO IIO

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