US2020458A - Telephone system - Google Patents

Description

Nov. 12, 19735. .1. F. DAHL v TELEPHONE SYSTEM Filed June 9, 1934 17 Sheets-Sheet l Nov. l2, 1935.

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17 Sheets-Sheet 1'7 UNITED Price Y 2,020,458 TELEruoNn srs'rEM Jack F. Dahl, Millburn,

Telephone Laboratories,

York, N. Y., a

N. J., assigner toV Bell incorporated, New

corporation of New York Application June 9, 1934, Serial No. 729,782

21 Claims. (Cl. 179-27) This application relates to telephone systems and more particularly to telephone systems in which the establishment oi connections involves more than one operator.

More speciiically, the invention relates to a modication of the operators equipment disclosed in Patent No.,1,753,3l8 granted to J. B. Newsom, April 8, 193() in which the operators equipment is located at a centralized oice in which no switching takes place. In such an arrangement, while automatic ringing is used at the terminating oice, it is desirable for'certain types of calls to place the start of ringing under the control of the originating operator. Depending on the nature of the call being handled, the operator may or may not wish to talk with the called party. Heretoiore it has been necessary for the originating operator to await a signal indicating that the called line has been reached before she could operate her ringing key. In accordance with the present invention, the originating operator may operate her ringing key as soon as she has passed the wanted line number to the control operator and the ringing signal is thereupon held in abeyance until the connection has been completed at which time it becomes effective to start the machine ringing equipment.

In trunking systems, such as the present, where an alternating current relay is connected across the trunk line to respond to an application of ringing current to initiate machine ringing,rthe surges of direct current which take place in the trunk due to disconnections, etc. are often sufcient to operate the ring-up relay falsely. To obviate this diniculty, in accordance with the present invention, the ring-up relay has two differentially wound windings which are connected in series with condensers, one to each side of the line, the opposite ends of the windings being connected to battery and ground. The ring-up relay is therefore responsive to ringing current applied to either side of the line but is unaffected by surges which occur over the two sides of the line.

The operators equipment used at the centralized office includes a, link circuit which interconnects the register sender and the trunk. Timing means is associated with the link circuit for giving an alarm if any of the functions of the -equipment is delayed unduly. Normally, this timing means causes the transmission of a signal to the trunk which in turn transmits the signal to the originating operator and releases the-operating equipment. However, in the case of a link circuit suspected of faulty operation, means is provided whereby' the operation of the timing means prevents the release' of one or more parts oi the equipment so that the cause of the trouble 'may be determined. At a certain stage of the operation only the link circuit is held and in that case the signal to the originating operator is not given. The signal transmitted to the trunk circuit causes the disconnectionof the outgoing supervisory relay from the trunk conductors and its connection to a source of battery and interrupted ground so that the supervisory signal at the originating office is intermittently operated as a reorder signal.

A clearer understanding of the invention will15`-i` be obtained from a consideration of the following description in connection with the accompanying drawings in which:

Fig. 1 shows in diagrammatic form the circuits shown in detail in the remaining drawings.

Figs. 2 andV 3 show Athe relay equipment of trunks of two types. l

Figs; 4to 8 and 11 show the link circuit for connecting the operators position equipment and sender with the trunk equipment.

Figs. 9 and 10 show the incoming selector in which the trunk of Fig. 3 terminates.

Figs. 11-A, 12, 14 and 15 show the sender.

Fig. 13 shows the position circuit.

- Figs. 16 and 17 show the incoming selector in 30` which the trunk of Fig. 2 is terminated; and

A Fig. 18 shows the manner in which the remaining figures are to be arranged.

Referring first to Fig. 1, the equipment at four telephone offices is disclosed, that is, equipment at office A, at a toll or long distance oice O, a centralized ofce B and a terminating ofce T. The centralized equipment at ofce B -may be employed in the completion of toll calls which, having been extended from the calling substation it@ at a local cnice A to a toll operators position at the office O, may be further extended by means of jack iti, cord 02 and jack |03 to the long distance trunk circuit I5() at the centralized office B. The establishment of a connection. with the trunk circuit causes the linkcircuit lEZ to associate itself with the trunk, with the position circuit 15d and with the sender E53. The link circuit first connects the incoming end of the trunk with the position circuit so that the toll operator may give the wanted number to the B operator. It then connects the position circuit with the sender to permit the registration of the number in the sender and then connects the sender with the outgoing end of the 55 trunk so that the sender may control the incoming selector |10 and the final selector |1| in the selection of the wanted line |12.

The centralized equipment may also be used subscriber reaches the A operator'over the dial equipment indicated by line inder II I and the trunk terminating in the plug I2. The insertion of plug ||2 in jack ||3 results in the seizure of trunk |5| and the same operations of the centralized equipment as for the long distance trunk. Trunk I5I is permanently connected to incoming selector which differs from the incoming selector I 10 in which the long distance trunk |50 terminated. However, rlnal selectors IBI and |1| may be of the same type. The incoming selectors |10 and |80 have .been shown as located at the same terminating oflice. However, it is to be understood that while each trunk passing through the centralized B oilce connects a particular originating oice with a particular terminating oiiice, each of a plurality of originating oilices may be connected to a plurality of terminating oflices'by groups of trunks which may be served by the centralized B oiice equipment.

Incoming toll call Referring now-to the detailed drawings, the subscriber at substation 200 in originating a call for a subscriber at substation |180 will be connected by suitable equipment with a long distance operators position having access through the centralized B oiiice with the oce at which substation |160 is located.

When the long distance operator inserts the calling plug of her cord 202 in the jack 203 leading to the trunk circuit of Fig. 2, a circuit is closed from battery through the right winding of relay 2| 9, resistance 2| I, right back contact of relay 2|0, lower left winding of repeating coil 204, over the ring conductor of the incoming inter-oilice trunk and through the repeating coil and supervisory relay in the long distance operators cord (not shown), back over the tip conductor to the upper left winding of repeating coil 204, left back contact of relay 2 I0, resistance 209 to ground through the left winding of relay 2|9. Rel-ay 2 I9 closes van obvious circuit for relay 2| 4 which in turn operates relay 2|3. Both relays 2| 4 and 2| 3 are slow to release to prevent a false release of the connection in case the incoming end of the trunk circuit is opened momentarily. Relay 2|4 also connects ground over its right front contact, right back contact of relay 2| 5, to resistance 2|1 in shunt of the winding of relay 2|8 to prevent its premature operation. In addition, relays a circuit from ground over the right contact of relay 2|4, back contact of relay 2|2, left front Contact of relay 2| 3, right winding of relay 2I0 to battery. Relay 2|0 closes a holding circuit for relay 2| 9 extending fromv battery through the right winding of relay 2|9, resistance 2|I, right front contact of relay 2|0, resistance 209, left winding of relay 2|9 to ground. Relay 2|9 remains operated independent of the control of the toll operator until the trunk circuit is closed through to the incoming selector circuit. Relay 2| 3 closes a circuit from ground at the upper normal contact of relay 206, inner right contact of relay 2|3, inner left back contact of relay 22|, winding of relay 222 to battery at the right back contact of relay 225. Relay 222 locks over its inner left :front contact to its operating ground independent of relay 22|.

The operation of relay 222 initiates the association of the trunk circuit with the operators equipment. It therefore connects ground over its outer left contact and the outer right back contact of relay 22| to the start conductor 23|. It also connects battery through resistance 234 over its inner right front contact and the inner right back contact of relay 22| to conductor 232 cuit from battery through the winding of relay 220, the middle right contact of relay 222, right back contact of relay 226 to conductor 233 which likewise terminates in a terminal of selector 100.

The connection of ground to conductor 23| completes a circuit which extends over the normal contact of jack 502, lower back Contact of relay 505, back contact of relay 526 through the winding of relay 5| 6 to battery over the upper back contacts of relay 5| 0. Relay 5|6 operates in this circuit closing an obvious circuit for the trip magnet 146 of the trunk nder. It also closes a circuit from ground over its outer upper front Contact, lower back contact of relay 5| 0, inner lower back Contact of relay 483, lower contacts of cam 626 to the winding of relay 8|9 and battery, to initiate the operation of the link circuit. A parallel circuit also extends from conductor 23| through the lower winding of relay 509 to battery.

The start circuit of Fig, 5 closely resembles that disclosed in the above identied Newsom patent and serves to prevent interference between calls originating in close succession. Relay 559 controls that part of the circuit which acts in case of trouble to delay the handling oi a call to sound an alarm and automatically disable the group of link circuits on which the trou.-I ble occurred. Relays 480 to 486 cooperate with the start circuit and function in case the motors driving a part of the trunk nders stop running. Fig. fl also shows portions of three link circuits for the purpose of indicating the method of allotting links for service. This is also disclosed in the above mentioned Newsom patent and will not be described in detail here.

When relay 8i@ is operated, it locks in a circuit from battery through its winding, over its inner left front Contact, right contacts of cam 6 IQ, left back contact of relay 620 toy ground over commutator strip 1|! and brush 1li). Another holding circuit is also closed for relay I9 over the lower right and upper left contacts of cam 0 I 9 which extends to ground over the commutator strip and brush 135 after the selector moves off-normal for the purpose of centering the brushes of the selector properly. With relay 8|9 operated, a circuit is closed from battery through the winding of sequence switch magnet 500, lower right contact of cam 501i, cuter lelt front contact of relay Sig, upper right and lower left contacts of cam SI2 to ground, advancing sequence switch 600 from position l. With sequence switch G00 in position 2, a circuit is closed from battery through the winding of the updrive magnet 1|4, upper contacts of cam 5 l 2, outer left front contact oi relay 8|9, over the lower right and upper left contacts of cam 608 to ground.

As the selector starts upward, ground is connected over brush 101 and commutator segment 108, left contacts of cam 69|, to the winding oi relay 5|@ and battery. Relay 5|0 locks over its inner lower front contact, left back contact of back contact of ating circuit of relay' i i2@ so long as relay i204 is held operated.

When relay ili operates in the reverse battery fundamental circuit, it closes a circuit from battery through the right winding of relay iliit, upper left contact of cam i632, lower right contact of cam i553 I, iront contact of relay il i 5, right contacts of cam ii! to ground over the upper contacts of cam i522. With relay illi operated in position 9 oi sequence switch itil!) a circuit is closed from battery through the winding of sequence switch magnet HUB over the lower left contact of cain H534, inner left Contact of relay ilfi to ground, advancing sequence switch itilil to position iii and thence to position ii over its normal cam. The reverse battery closure is maintained through position ii! to insure the 'operation ci the sender relays, but when sequence switch itil@ reaches position ii, relays ili5 and ilill release.

When sequence switch itil@ reached position tl/fx battery through the left winding of relay Het is connected over the upper contacts of cam i625 and the upper back contact of relay iili to the upper leit winding of repeating coil iiiii, and the upper terminal oi condenser iiiii, while the lower terminal o the condenser and the lower lett winding of repeating coil @tot are connected over the lower back contact of relay itiiR to ground over the left contacts of cam W33.

When sequence switch iiiilil reaches position i i, battery through the left winding oi relay ile@ is extended from the upper leit winding oi repeating coil iil over the upper contacts oi iiii to the'tip conductor Zii of the inter-cnice trunk. As sequence switch leaves position iii, the ground above traced is disconnected and when the sequence switch reaches position ii, the ring conductor 2432 of the inter-cnice is extended over the upper contacts oi cam itis, lower left winding of repeating coil i592?, lower relay les?, right winding ofrelay il to gr und over the lower contacts of cam itil. rI'he incoming selector Vnow awaits trunk closure by the link or trunk circuit. Y,

ln the sender when the reverse battery circuit is opened, relays H3@ and iid@ operate in the circuit closed by relay i263. Relay iid@ opens the fundamental circuit in the usual inanner and relay i itt closes a circuit from grounded conductor titi, front contact ci relay litt through the winding o relay iii to battery over the left front contact oi relay i293. Relay ldt, in operating, opens the locking circuit for relay itil@ and that relay releases. Relay i255@ also disconnects ground at its leit back contact from conductor li.

The removal of ground from conductor lt! indicating that the sender has completed its iunction, opens the circuit of relay tit which now releases closing a circuit from battery through the winding oi sequence switch magnet tilt, upper left contact of cam ttt, left back contact oi relay Si@ to ground over the lower right contact of cam tiet, advancing sequence switch iil to position 9 trom whence it is advanced to position il over its local carn. As soon as sequence switch til@ leaves position 81/2 ground is disconnected from conductor li releasing relay iilil and disconnecting ground irom oit-normal conductor it i, thereby releasing all relays which are locked to that conductor and, since it removes ground from conductor i222, releasing all oi the register relays and putting the sender in condition to controlA another call.

As sequence switch til'passes through positions i21/2 to IBI/4 a circuit is closed iront the tip conductor 24! of the inter-office trunk which was connected as previously traced to battery through the right winding of relay ili over the left alternate contact of relay 226, conductor 23l, brush li, middle right Contact of relay Bit, inner right front contact of relay Bi through resistance Eil, lower right and upper leit contacts of cani till, outer right back contact of relay Bill, brush lt?, conductor 238, over the inner left front contact of relay 225 through resistance 23!! to the ring conductor 2&2 and thence to ground through the left winding of relay il as above traced.

When sequence switch Gti) reaches position i3, battery through resistance tit is removed from conductor 232 thereby releasing relay 22l but since relay 223 is still operated, the locking circuit of relays 2.2i and 226 is maintained and a circuit is closed from ground over the back contact o relay Ztl, inner right front contact of relay 22%, outer right front contact of relay 2222, through the winding of relay 29E, resistance right back contact of relay 225 to battery. Relay 256, in operating, closes a locking circuit for itself rorn battery over the back contact of relay resistance 239, winding o relay 2%, outer upper front contact of relay 2% to ground. Relay disconnects ground from the holding circuit of relay 222 which now releases. Relay 2% also connects the tip conductor Zfii of the interoiice trunk over its inner upper iront contact, upper back contact of relay 205, upper right winding of repeating coil 2M, back contact of relay 22h, winding of relay 2i2, lower right winding of repeating coil 2M, lower back contact oi' relay 2535, inner lower front contact ci relay let to the ring conductor Zl of the inter-oce trunk, thereby making a second trunk closure which overlaps the trunk closure made by the link circuit.

Relay ilu?, operates in response to the trunk closures by the link and trunk circuits, completing a circuit from ground over the lower left and upper right contacts oi cam i633, front contact of relay H08, lower contacts ci cam itat through the winding oi relay Het to battery. Relay ilse closes an obvious circuit for relay il which closes a substitute ground to the right winding o relay il. It also connects ground over its inner left front contact, left contacts oi cam iti, upper right contact of cam itl to battery through the winding oi sequence switch magnet iit, advancing the sequence switch to position i2 and in this position ringing and talking take place.

When sequence switch tot leaves position iii, battery through resistance Si@ is disconnected from conductor 233 thereby releasing relay which in turn releases relays 22! and 22e. The link circuit is thereby completely disconnected from the trunk circuit.

When sequence switch (itil reaches position iii, a circuit is closed from battery through the winding of relay titl, upper contacts of cam @i i, coinrnutator strip lili, brush li2 to ground, Relay iii@ closes a circuit from battery thro-ugh the winding of downdrive magnet lit oi the trunk nder ltd, left front contact of relay @.i, right contacts of cam ii to ground, restoring the trunk finder to normal. When the trunk iinder reaches the bottom of its bank, brush li?. leaves coinmutator strip lit and relay tit releases, in turn releasing downdrive magnet H5.

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