US759771A - Signal apparatus for telephone-switchboards. - Google Patents

Description

No. 759,771.. PATENTED MAY 10, 1904.

DE WITT U. TANNER. SIGNAL APPARATUS FOR TELEPHONE SWITGHBOARDS.

APPLICATION FILED MAR. 27, 1902.

H0 MODEL.

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fkzwjzw 176 j 7 rZMMVmM/k UNITED STATES DE WVITT C. TANNER, OF CHICAGO,

Patented May 10, 1904.

PATENT OFFICE.

ILLINOIS, ASSlC-NOR TO 'WES ERN ILLINOIS.

SIGNAL APPARATUS 0R TELEPHONE-SWITCHBOARDS.

SPECIFICATION forming part of Letters Patent N0. '7 59,77 1, dated May 10, 1904.

Application filed March 27, 1902.

T0 aZZ whom, it may concern.-

Be it known that I, I) E Wirr C. TANNEI-i, 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 Improvement in Signal Apparatus for '.l.ele phone-Switchboards, of which the following is a full, clear, concise, and exact description.

My invention relates to telephone-exchange systems; and its object is to provide improved apparatus by which the call of a subscriber for a connection and a subsequent clearingout signal from both the subscribers who have been connected may be automatically indicated to the central-oflice operator.

In accordance with my invention the linesignal, which is automatically displayed to call the central ofiice, is efl aeed when the operator answers the call, serving thereafter as a clearing-out signal, the display of which will indicate that the connection may be taken down. In completing connection to the called line the signal is brought under the control o'l. both lines jointly, so that the apparatus of both must cooperate to cause the display of the signal. In making connection with any line in response to a call from another the line-signal ot' the called. line may be blocked to avoid confusion, the signal of the callingline only being operative. The calling plug or switch, which completes connection to the called line, may be arranged to close a shunt of the line-signal of that line to render the same inoperative; and a further feature of my invention consists in the combination, with such an arrangement, of a battery in the shunt of insufiicient strength to actuate the signal, but suflicient to establish a recognizable test potential as soon as the connection is made and independent of the line-battery, which can be applied to the test-contacts only by the line relay switch and. which consequently is applied only while the telephone is in use at the substation.

I will describe my invention more particularly by reference to the accompanying drawing, which is a diagram illustrating two subscribers telephone-lines extending from sub- Serial No. 100,208. (No model.)

stations to a central-ol'fice switchboard, with a pair of plugs and their plug-circuit for uniting the lines, the system being organized and equipped inaccordance with my invention.

Each telephone-line extends in two limbs 1 2 from the substation apparatus to the usual multiple spring-jacks at the central oflice and thence through the high-impcdance windings a a, respectively, of the line-relay a to the poles of the battery I). At the substation the usual telephone apparatus is provided in a bridge of the line controlled by the usual gravity telephone-switch, said bridge being closed by the switch when the telephone-receiver is removed from the hook for use. The spring-jacks c are of the usual type, each having short and long line-swings 0 0 connected, respectively, with the limbs 1 2 of the telephone-line, and also having a third contact or test ring c, which is connected by a conductor 3 with the front contact of the line-relay a. The armature of said line-relay is connected through a resistance n with the free pole of the grounded central battery 7). The line- 'signal may be an incandescent lamp of in a branch 4 to ground from the test-ring c of the answering-jack. When the line-relay is excited, therefore, a local circuit is closed from the battery 7) through the resistance a and conductors 3 4-, including the lamp (1, to earth.

The plugs) g, by which lines are united, each have the usual tip, ring, and sleeve contacts, which are adapted to engage the short andlon'g line springs and the testa-ing, re spectively,", 01 any spring-jack into which the plug maybe inserted. The plug 7" is the answering-plug and g is the ealling-plu9z The tip and ring contacts f" f of the answeringplug are united with the corresponding contacts g r of the calling-plug by the link conductors 5 6 of the plug-circuit, which include the windings of the usual repeating-coil. The batteryb is connected in a bridgeof the plugcircuit between the windings oi the repeatingcoil in the usual inaimer, and a supervisory relay 7:. is coimected in one of the cord-strands between the battery 7) and the calling-plug, said supervisory relay being thus controlled by the telephone-switch at the substation of the line whose jack is plugged into.

A conductor 7, having two branches, which are alternatively closed by the supervisory relay it, terminates in the third contact f of the answering-plug, so that when the answeringplug is inserted in the spring-jack of a calling-line said conductor 7 is brought into parallel with the line-signal (Z of such line. One of said branches of said conductor 7, closed by the relay Zr when excited, is of low resistance, adapted to shunt out the line-signal (Z when broughtinto parallel therewith, and the other branch, which is normally closed in the resting contacts of the relay it, contains a battery suitable for actuating the line-signal of the calling-line when placed in circuit therewith, said battery, however, being connected to oppose and neutralize the flow of current from the line-battery through the signal, so that said signal will not be excited when both batteries areapplied thereto. The sleeve of the calling-plug may be connected, through a resistance Z: and a portion of battery Z, to

earth, the resistance in being low enough to shunt out the line-signal of the called line when brought into parallel therewith. If the line-battery has an electromotive force of twenty-four volts, as is usual, the line-lamps (Z may be twelve-volt lamps. The resistances 0 may be one hundred and twenty ohms. The resistances 73 and Z2 may be forty ohms each. The battery Z may be so proportioned and connected througha conductor of such resistance as to supply an electromotive force of twelve volts to conductor 7 to light the lamp (Z when the branch 3 is opened and to oppose the battery Z and prevent the lighting of said lamp (Z when the branch 3 is closed. The portion of said battery which is connected through the resistance Z1 with the sleeve of the callingplug may have an electromotive force of four volts.

The operation of the system is as follows: A subscriber desiring an exchange connection removes his telephone from its hook and thereby completes the circuit from battery Z over the line through the windings of the line-relay a, which thereupon becomes excited and draws up its armature. The local circuit 3 4:, including the line-lamp (Z, is thus closed and the lamp is lighted, indicating to the operator that a connection is desired. The operator responds to the call by inserting her answer-.

relays have dropped back. hen relay is excited and relay Z1 inert, as is the case until the called party responds, the battery Z is brought into connection with the lamp (Z and sets up an electromotive force opposite to the electromotive force applied by the battery Z, so that the lamp is extinguished. As soon as the called party responds the armature of magnet h is drawn up, cutting off the battery Z, but at the same time connecting conductor 7 to earth through the resistance Z, which shunts the lamp and prevents its illumination. If while the magnet Zb is excited the relay (1. allows its armature to drop back, the lamp (Z is simply left included in the circuit 7 4, which has no battery connected therewith, so that the lamp remains dark; but when both relays allow their armatures to drop back the connection of battery Z with the line-lamp of the calling-line is cut oif and the battery Z applied thereto in the local circuit 7 4, so that said lamp is lighted to indicate a clearing-out signal.

hen the calling-plug g is inserted into the springjack of any line, a test potential is applied to the test-rings of the several multiple spring-jacks from that portion of the battery Z which is connected through resistance 7:; to the thirdcontact of said calling-plug, so that an operator at any section on the multiple switchboard may make the usual busytest, touching the end of her calling-plug to the ring of the line being tested and listening in her telephone for the click which is produced by the test potential. When the called party responds, the armature of his linerelay will be drawn up, but his line-lamp will be shunted out by the resistance k. The portion of battery Z which is connected to the third contact of the calling-plug while suflicient to establish a recognizable test potential is not sufiicient to light the linelamp of the called line when the line-battery thereof is cut ofi". The line-lamp of a line, therefore, is never lighted when connection is made with said line in response to a call from some other line. The line-signal of a calling-line is displayed to indicate the call; but when the operator answers the call the signal is efiaced and brought under the joint control of the telephone-switches at both the calling and the called stations, being thereafter displayed as a clearing-out signal when both parties have hung up their telephones.

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

1. The combination with two telephone-lines each extending from a substation to a central oflice, of link conductors at the central ofiice for unitingt he lines, a source of current connected with the lines at the central oflice, a switch at each substation controllingthe flow of current in its line, electromagnetic mechanism normally associated with one line,

IIO

other electromagnetic mechanism connected with said link conductors and temporarily associated with the other line, said electromagnetic mechanism of each line being responsive to the flow of current therein, and a signal permanently associated with one of the lines and controlled jointly by the electromagnetic mechanism of both lines.

2. The combination with two telephone-lines and link conductors at the central o'fiice for uniting them, of magnets one for each line one magnet being permanently connected with one line, and the other magnet being associated with the link conductors and temporarily rcsponsive to current in the other line, said magnets being controlled respectively through the agency of switches at the substations of said lines, a signal permanentlyassociated with one line and normally controlled by the magnet thereof, and means made operative in uniting the lines for bringing said signal under the cooperative control of the magnets of both lines.

3. The combination with a calling-line and a called line of a line-relay for the calling-line and a supervisory relay for the called line, said relays being controlled by switches at the respective substations, a line-signal for the calling-line controlled by the line-relay thereof, link conductors for uniting the lines, and circuits established in uniting the lines for connecting the line-signal of thecalling-line with contacts of the supervisory relay of the called line, to bring said signal under the cooperative control of both of said relays, whereby the line-signal 01' a line may first indicate a call and thereafter serve as a disconnect-signal controlled jointly by both lines.

4. The combination with a local circuit containing a battery, a resistance and a signal, of a switch controlling said circuit, a conductor having two branches with a switch for alternatively closing either branch, one of said branches containing a second battery, and the other branch being of low resistance, and a switch for connecting said conductor in parallel with the signal, said last-mentioned battery being connected and adapted to oppose the [low of current from the first battery through the signal to prevent the actuation of said signal when both batteries are applied thereto,

said second battery being adapted to actuate the signal when connected therewith independent of the first battery.

5. The combination with a calling-line and a called line and the line-relays thereof controlled by switches at the respective substations, of a signal for the calling-line in a local circuit controlled by the line-relay thereof, said circuit containing a battery and a resist ance, link conductors for uniting the lines, a supervisory relay adapted to be connected through said link conductors with the called line and controlled through the agency of the switch at the called station, and a conductor? brought into parallel with the line-signal of the calling-line in making connection therewith, said conductor having two branches controlled by said supervisory relay, one of said branches, closed by the supervisory relay when excited, being adapted to shunt out the linesignal, and the other branch, closed by said supervisory relay when inert, containing a battery, said last-mentioned battery being c011- nected and adapted to neutralize the line-battery, but being adapted to actuate the signal when the line-battery is disconnected.

6. The combinationwith a telephone-line having multiple spring-jacks with test-contacts, of a line-signal in a branch from the test-contacts of the spring-jacks, a source of current in a second branch from said test-con tacts, forming a local circuit with the firstmentioned branch containing said line-signal, switch-contacts of a line-relay controlling the branch containing the source of current, a plug and plug-circuit for making connection with the line at one of the spring-jacks thereof, a shunt of the line-signal closed in registering contacts of the plug and spring-jack, and a source of current in said shunt, serving to establish a test potential at the spring-jacks while the first-mentioned source of current is cut off, but being insufficient to actuate the line-signal.

In witness whereof I hereunto subscribe my name this 15th day of January, A. D. 1902.

DE WVITT (J. TANNER.

Witnesses:

Giuonen P. BAlrroN, E. H. ELLE'LT, Jr.

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