US1681015A - Automatic telephone system - Google Patents

Description

Aug. 14, 192s.

N. H. SAUNDERS AUTOMATIC TELEPHONE SYSTEM Filed March 31, 1927 l2 Sheets-Sheet 1 y F11 .J

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Norm an H. Eaundans Aug. 14, 1928.

N. H. SAUNDERS AUTOMATIC TELEPHONE SYSTEM Filed M5291; QT, 1927 Norm an H. E aunder's Patented Aug. 14, 1928.

UNITED STAT-Es .PATENT oFEIc-E.

NORMAN H. SA`UN`DERS,-OF HOMEWOOD, ILLINOIS, ASSIGNOR TO RESERVE HOLDING COMPANY, OF KANSAS CITY, .MISSORL A .CORPORATION 0F DELAWARE.

AUTOMATIC TELEPHONE SYSTEM.

Application led March 31, 1927. Serial No. 179,782.

The present invention relates to automatic telephone systems in general7 but is concerned more particularly With automatic telephone systems containing subscribers lines of different characters. The invention is furthermore concerned especially with telephone systems in which almost all the lines are of onecharacter, while only a very small number of the lines are of another character.

In explanation of the foregoing, it may be pointed out that it has become standard practice in automatic telephone exchanges wherein the switchesare operated in accordance with the S40-called two-wire control circuit to arrange all lines that are of a relatively short length for loop operation 1n Controlling Athe automatic switches, and to arrange .the longer lines, for example those extending into the ,rural `territories for controlling the automatic switches over a socalled simplex circuit (two sides of the line in parallel and a ground return). It has `become standard practice in telephone eX- changes wherein there are only a Vfew rural lines, say a dozen or less, to provide each rural line with a simpleX-to-loop repeater individual thereto between the vline and its individual line switch. When this is done, the exchange switches Ymay be all'of standard loop type.

Another problem involved in the forego ing situation is the provision of arrangements for signalling the various stations on the simplexed rural lines, as these lines are practically always party lines, the ringers being operated `according to predetermined codes to .sign al the various stations.

It is an object of the present invention vto provide a code selector individual to each party line arranged to respondto the oper-y ation of the calling device on a calling line after a connection has been ,extended to the called line to select the particular code necessary to signal the called station.

Itis a` further object ofthe invention to combine this code selector with the individual line repeater in such a manner as to reduce the required equipment.

A further object of the .invention is to royide suitable circuit arrangements wherey the code select-or maybe set by' impulses transmitted over a non-talking conductor from a calling connector after the connector has seized the line.

A further object of the invention is .to provide suitable circuit arrangements whereby a connector of the so-called rotary type,

'having a fourth wiper used as a rotary test wiper, may be arranged so that the same fourth wiper is utilized for the transmission of impulses to set thecode selector.

A still further object of the invention is the provision of suitable arrangements `for. maintaining -a line busyl after the calling connector has released until the code selector -has returned to its normal position.

A still further object of the invention is the provision ofsuitable arrangements so that the ringing current ordinarily transmitted by the connector is Vnot effect-ive in `reaching/the called line so as vto avoid a con- 4by means of the usual circuit diagrams a sufficient amount of apparatus in a telephone system embodying the features of the invention to `enable the invention to be understood.

l Fig. 1 shows a connector arranged to be operated according Vto vthe well known loop method of two-wire control and arranged `to rotate automatically to find an idle line in a group in case vthe call is for one line of a `group of lines. and it is arranged to cooperate with the 'repeater and code selector shown in Fig. 2.

Fig. 2 shows the repeater R and the associated code selector CS individual to the line of substation B. The distributor` D and the associated equipment are provided for placing the necessary codes on the bank of the code selector CS so as to secure the proper operation of the ringing relay 207. rIhis ringing equipment is, of course, common to al1 the repeaters and code selectors.

The line ot substation A is assumed to be one line of a group belonging to the same subscriber. the connector C being arranged to complete a connection to the first line in the group tound to be idle. The line of substation B is a party line common to ten substations. In the connector C, the first level has been reserved for party lines such as the line ot' substation B, it being assumed that there are not more than ten such lines in the exchange. The first level springs associated with wiper 115 are arranged to operate only when the wipers have been raised opposite the first level These springs may be operated by a suitable cam arrangement on the shaft ot tne switch. 'The wiper 115 is shitted from the rotary test circuit to the impulse circuit when the wipers are opposite the firstl level so as to enable the wiper to periorm both functions assigned to it.

The apparatus having been described generally, a detailed description ot its operation will now be given. For this purpose it will be assumed first that the connector C is seized over conductors 110-112 in connection with a call to the group ot lines containing the line of substation A. Vhen the connector is seized b y a selector switch, as is usually the case, conductor 111 grounded by the seizing switch, thereby making the connector busy to the other selectors having access to it. Then conductor 111 is so grounded, a connection is closed through the ott-normal contacts associated with the upper winding ot the relay ytor the combined ring-cut-oft and change-over relay 105. Relay 105 operates and disconnects the associated impulse conductor from the rotary magnet and connects it instead to the vert-ical magnet, at the same time preparing a locking circuit for itself. In response to the seizure of the connector, line relay 102 is operated over conductors 110 and 112, closing a circuit for release relay 103. Release relay 103 operates and prepares the impulse circuit and opens a point in the release-magnet circuit. Relay 103 also places ground on conductor 111 so as to maintain the connection intact atter the slow acting release relay of the seizing selector has fallen back. Release relay 103 also places ground on the locking conductor 123.

lhen the calling subscriber dials the next digit 2 in the desired number. line relay 102 falls back twice momentarily, each time grounding impulse conductor 124 through an armature of release relay 102, and armature ot busy relay 106, and series relay 107. Since conductor 124 is at this time connected with the vertical magnet, i the vertical magnet is operated twice momentarily, raising the wipers 113-116 opposite the second level of bank contacts. Relay 108 is normally connected to the impulse conductor 124 so that it will operate quickly when the first impulse is delivered. Relay 107 operates in series with the vertical magnet and connects relay 108 to ground. at the same time disconnecting it from the impulse conductor 124. Relays 107 and 10S remain operated throughout the series o1' impulses. Relay 108, at its upper armature. completes the locking circuit ot the upper winding of relay 105 to the grounded locking conductor 123, thereby maintaining relay 105 operated after the ott-normal springs have opened on the first vertical step ot the switch.

At the end ot the vertical movement, relay 107 'falls back and opens the circuit of relay 10S. whereupon relay 1.08 falls back after a slight hesitation and opens the locking circuit of relay 105, the ofi-normal springs having previously opened. Relay 105 falls back and transfers conductor 124 from the vertical magnet to the rotary magnet.

Vhen the next digit, is dialled, relay 102 'f falls back a 'corresponding number of times, grounding,conductor 121i each time it does so. As a result, the rotary magnet operates and brings the wipers 113-110 into engagement with the desired contact. set in the second level. Relays 107 and 10S are again operated in the above described manner. Relay 107 opens the connection between stepping relay 104Y and the rotary test wiper 115. and relay 108 closes a point in this connection. At its inner upper armature, relay 108 disconnects test wiper 114; from the test winding ot switching relay and connects it instead to busy relay 100, at the same time opening a point in the locking circuit of the busv relay. Relay 10i' at its inner lower armature places a shunt around the associated armature and contact ot relay 100 so as to maintain the rotary magnet circuit intact during the directed rotary movement in case busy relay 100 should operate due to test wiper 111i passing over test contacts of busy lines. At the end ot the directed rotary movement, relay 107 falls back and busy relay 100 operates through test wiper 114 it the first line of the group is busy. Assume that the first line of the group is the line of substation A and that the line is busy. lu this case, relay 107, upon falling back, con'ipletes the connection between wiper 115 and stepping relay 104, whereupon relay 101.- operates owing to the connection existing between the rotary test contact and the regular test contact through the jumper 117. Upon operating, relay 10-.1- locks itself to the ground release trunk conductor 111 at its upper armature through the interruptor contacts of the rotary magnet.y At its lower armature it places ground on impulse conductor 124 on t-he rotary-magnet side of series relay 107. The rotary magnet thereupon operates again and advances the wipers another step. A circuit is closed for relay 108 in multiple with the rotary magnet so as to maintain this relay operated during the automatic rotary movement of the connector. Relay 10T is not reoperated however, due to the point in the circuit at which the connection to the operating conductor is made, Near the end of the stroke of the rotary magnet, the interrupter springs are opened, whereupon stepping relay 104.- falls back and opens the rotary magnet circuit. The rotary magnet again falls back and connects up the stepping' relay again. It the second line in the group is busy, the stepping relay is again operated whereupon the wipers are advanced into engagement with `the third line of the group. This rotary movement continues until an idle line is reached or until the last line of the group is reached. The last line of the group does not have a connection between the regular testand the rotary test contacts, with the result that the stepping relay cannot reoperate when this line is reached. In this case the rotary movement is stopped and relay `108 falls back and closes the locking circuit of busy relay 106, at the same time completing a connection from the busytone conductor tothe lower talking conductor so as to enable the calling subscriber to hear the busytone so that he will be reminded to replace t-he receiver and attempt the connection later.

Assuming now `that the line oi substation A is the first line in the group and that it is idle when called, busy relay 10G is not operated when the wipers land on the coiit-acts of the line, in which case the deenergization of relay 10T is followed by the deenergization of relay 106. Then relay 108 falls back, a connection is completed between release trunk conductor 111 and test Wiper 114 through the test winding or relay 109 and contacts oit' relays 106 and 108. The circuitof this test winding is completed to battery through the cut-ofiI relay of the line switch (not shown) over 'conductor'll Thecutoit' relay and relay 109 operate in series.

The cut-ofi' lrelay clears the `called line/of its battery and ground connections. Relay 109 closes a locking circuit from conductor 123 to its own lower winding; places ground directly on test wiper 114; prepares a new locking circuit for ring-cut-o'ff relay 105; opens the rotary-magnet circuitso as to prevent further rotation of the wipers of the switch; opens a point in the circuit of busy relay 106'so as to preventa false operation of this relay upon the release of the Conner tion; and at its upper and lower armatures lit connects up `wipers 113 `and 116 whereupon ringing current from the generator connected between the ringing lead and battery is projected out over the upper talking conductor, returning to ground over the lower talking conductor and contacts of relay 105 and 109.

lVhen the called subscriber responds by tween the windings ot line relay 102 and conductors 110 and 112, thereby reversing the direction of current flow in the conductors incoming to the connector for the purpose ot'V 'giving supervision or operating a meter, or the like, depending of course upon the origin ot the call; Relay 101 also opens a 4point in the circuit of the release magnet so as to prevent a premature release of the connector, and it places a` multiple ground connection on the locking conductor 123 so as to prevent this conductor from being prematurely ungrounded. A

The two subscribers may now converse with each other in the usual manner. Then the conversationhas terminated, they both replace theirreceivers. `Vhen the receiver is replaced at the called substation, in case this isdone first, relay 101 `falls back and prepares the release magnet circuit and reverses the current flow in conductors 110 and 112 to normal. When the calling sub` scriber hangs up under these circumstances, the deenergization ot line relay 102 is followed by the deenergization ot relay 103, whereupon the connection is released by the operation of the release magnet through an 4obvious circuit- In the interval required for relay 103 to fall back, relay 10S operates, but its operation is of no particular utility or consequence at this time. This relay falls back after relay 103 lets go. Relays 105 and 109 tall back responsive to the removal of ground potential from conductor 123.

Assuming now that the calling subscriber' hangs up before the receiver is replaced at substation A. relay 101 is still operated when line relay 102 falls back. Relay 108 operates as before and opens the connection between the grounded test wiper 114i and release trunk conductor 111 (through the upper winding ot relay 109 and contacts of relays 106 and 10S) so as to permit the release of the connection to take place with the ground potential maintained on the test wiper 114 by relay 109. Vhen re1ay103 falls back, it

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removes the ground potential trom conductor 111 so as to enable the preceding switches to release. The release magnet is not operated because relay 101 is operated, and conductor 12S remains grounded for the same reason. Relay 10S falls back a n10- inent after relay 103 falls back and removes ground trom the operating conductor. Relay 10S closes the connection between the grounded test Wiper 114 and release trunk conductor 111 so as to guard the connector against reseizure while it is being held by the mmreplacement of the receiver atsubstation A. The connection between wiper 111- and conductor 111. it will be noted includes the upper winding ot relay 100. The resistance ot this upper windingis sutliciently-low to permit. the guarding of the connector to be etl'ectively accomplished.

llvlicn the subscriber at substation A replaces his receiver. relay 101 falls back and closes the release-n'iagnet circuit. at the same time removing ground trom conductor 123. The connector is restored to normal position in the usual manner and relays 105 and 100 l'all back.

It will now be assumed that the connector C is seized in a call to substation B. lVhen the connector is seized. it prepared tor operation in the usual manner and the vertical movement takes place in the hereinbetore described manner when the first digit 1 is dialled. the wipers 11B- 110 being at that time raised opposite the first level of bank contacts. The middle one of the first level springs associated with the rotary test -wiper 115 is shifted to the lett.. disconnecting this wiper from the rotary test circuit and connecting it to a disconnected branch ot the impulse conductor 124. lVhen the next digit ot" the number is dialled. the rotary movement takes place in the hereinbctore described manner. rlhe result is that wipers 113-110 are brought into engagement with the bank contacts terminating the conductors 110-122 Il" the line is busy when called, there is a ground potential on conductor 120, with the result that busy relay 10G is operated and it locks up when relays 10T and 100 have fallen back. giving the falling subscriber the busy tone. Assuming that the line is idle. the busy relay is not operated and switching relay 100 operates through its upper winding aiter relay 10S has :fallen back. its` circuit being completed to battery over conductor 120 through the eut-oil relay ot the associated line switch. A branch circuit to battery is completed through contacts ot relays 203 and 201. Fig. 2. to battery through the winding of relay 203. Relay 203 operates at the same time that the eut-ofi relay ot the associated line switch operates. At its lower armature. relay 203 opens a point in the self-restoring circuit of the code selector CS. At its upper armature, relay 203 locks itself to conductor 120, at the same time opening its initial circuit so as to prepare the sclt-lmsying circuit which comes into play upon the release of the repeater and code selector'.

ln the connector' C. relay 101') operates and pertorms the hereinbefore described functions including the connecting up of the wipers 1131 and 11G. At its middle lower armature. relay 100 disconnects conductor 117-1 trom the rotary magnet and extends it through the shifted first-level springs, wiper 115. and conductor 121 to thc olicratingz,r magnet of the code switch (ffii. Fig. 2, through contacts o t relay 201 and the winding of the .series relay 202.

lfhen the calling suliscriber dials the next and last digit in the numliier. a series of impulses is transmitted over conductor 111- of the connector (l to the operating magnet of the code selector. 'l`he operating magnet re .sponda to these impulses and advances the wipers 20S and 200 one step lor each impulse. bringing wiper 200 into engagement with the bank contact. terminating the c0rrect ringingr code conductor. The slow acting series relay 202 operates at the beginning ot the impulsing and remains operated until the last impulse has terminated. lVhen rclay 202 t'allsl back it completes a circuit for relay 201 through wiper 208 and the bank contact on which it is standing. Relay 201 rmerates and opens the impulse circuit; preparcs` the pickaip circuit; and places ground on the disctmnected branch ot conductor 120. s soon as the distributor l) arrives in the pick-up position shown in the drawings, a circuit is closed tor pick-up relay 201. Pickup relay 201- operates, locking itself to conductor 210 and closing the connection bctween, the, ringing relay 20T and the code selector wiper 200. The code selected by wiper 200 is now impressed on ringing relay 20T. which relay responds and signals the called station in accordance with his preassigned code.

Then the subscriber at substation B responds by removing his receiver. the usual transmitter and receiver circuits are closed at. the switch hook contacts. and ground is placed on both conductors ot the called line, through the lower switch hook contacts. the impulse springs of the calling device. and the ringer coils. lVhcn this occurs. answcr ing relay 200 in the repeater l1 is operated with relay 207 in its normal position. Relay 206 operates relay 205. Relay 205 locks itself operated and opens the connection between relay 207 and wiper 200 so as to prevent further application of ringing current. Relay 200 also closes a bridge across conductors 119 and 122 through thc lett-hand repeating-coil windings so as tooperate the ring-cutot and hack- bridge relays 105 and 101 of the connector D. .lt will he apparent that the ringing current-from the connector C is unable to reach the line of substation B prior to the operation of relay 206, and that such ringing current is immediately removed by the operation oithe ring-cut-oiii' relay 105.

The two subscribers may now converse with each other `in the usual manner.

It' the subscriber at substation B replaces his receiver lirst, answering relay 206 iialls back and opens the bridge across the talking conductors at this point, resulting in the deenergization of back-bridge relay 101 of the connector C so as to permit the release of the connection as soon as the calling suhscriber replaces his receiver.

However, if the calling subscriber replaces his receiver lirst, the connection is heldy up due to the continued energization of backbridgerelay 101 until the called subscriber replaces his receiver, at which time relay 206 falls hack and permits the deenergization of hack-bridge relay 101. When the connector C releases, it removes ground from conductor 120, permitting the cut-oli relay of the associated line switch to releac and permitting relay 203 ot the repeater R to restore. When relay QOi-estores, itdisconnects itself from conductor 120 and connects conductor 120 to ground through the upper arniature` ot' relay 201, thereby replacing the busy condition ontihe conductor 120 so as to prevent the line from being seized again until the code selector has reached its normal position. At the lower armature of relay Q03, the operating magnet of the code selector is connected to the groundedv conductor 210 through its own interruptor contacts, with the result that the magnet is operated in a buzzer-like 'manner to advance the wipers 208 and 200 to their normal position. IVhen wiper Q08 reaches its normal position, it removes ground from` conductor 210, stop ping the operation oi the operating magnet and deenergizing relays Q01, 20-1, and i205.

Assuming now that the subscriber at suhstation B desires to originate a call, relay 206, operating as a line and impulse relay responds when the two conductors oi the calling line are grounded at the lower switch hook contacts through the impulse springs of the calling device. At its upper armature, relay 206 completes a bridge across conductors 119 and 122,causing the associated line switch to operate in the usual manner to extend the connection to a first selector. Vhen the calling subscriber operates his calling device, the circuit of relay 206 is interrupted a corresponding number of times, causing the automatic switches to operate over a loop circuit including conductors 119 and 122 in the same manner as when an ordinary common battery line is calling. There is an incidental operation of 21`In a party-line automatic telephone system, a plurality o'l' party lines, means for .setting up connections to any party line, andk station selectors associated with said party lines all located at a common point andV operable to select any desired called stations after the connections have heen set up to the lines.

3. In a party-line automatic telephone system, a connector switch operable over a calling line to setup a connection to a called party line, a station selector associated with the called line, means including an operating magnet for operating said station selector' to signal any desired called station on the line, and anl impulse circuit for said magnet including a wiper of said connector.

l. In a combination party-line and nonpartfy-line telephone system in which the' non-party lines may be arranged in groups with a single line call number per group, a connector having' access to groups of lines and having a rotary test wiper to enable it to rotate over busy lines to choose an idle line in a called group, a group oi party lines terminating in the bank of said connector, station selectors associated with said party lines, an impulse circuit t'or any selected stations selector including an impulse conductor in said connector and a branch impulse conductor individual'to the station selector, and a shifting device in said connector operated when a party line is called to shift said rotary test'wiper from the rotary test circuit into connection with said impulse conductor to complete the impulse circuit to the selected station selector.

5. In a telephone system, a rotary connector having a regular test wiper and a rotary test wiper, an` impulse conductor in said connector over which the magnets of said connector are operated, and contacts operated only in case certain lines are called :for shifting the rotary test wiper from the rotary test conductor to said impulse conductor.

6. In combination with a party line, a combined code selector and impulse repeater individual thereto, said code selector being arranged to select the correct ringing code when the line is called, and the repeater belli) ing arranged to repeat switch operating impulses to the central ollice apparatus when the line is calling.

'l'. In a party line telephone system, a. party selector individual to a party line, means for extending a connection to said line and lor subsequently operating said selector to select the desired called party on the line, means included in the connecting means lor maintaining the called line busy to other connecting means until the connection is released, means for releasing said code selector responsive to a breaking down of the established connection with a line, and means in the code selector for replacing the busy condition on the line and for maintaining it until the code selector is released.

8. In a telephone system.4 a plurality of party lines, each line having a directively operated device individual thereto i'or signalling any desired station thereon, directively operated switching means itor select ing any desired line, and means lor. transmitting digit impulses trom said switching means'to the device ol' a selected line for operating the device.

9. In a telephone system. a rotary connector having directive and automatic rotary movement, a. wiper for controlling the automatic rotary movement, and means for transmittincr digit impulses over .said wiper.

l0. In a telephone system, a party line.I means individual to the party line controlled by digit impulses to signal a desired station on the. line, a connector having access to said line. said connector having a pair ot' talking conductors terminating in Wipers, a special wiper, and circuit arrangement t'or transmitting digit impulses from the connector over said special wiper to said first-mentioned means.

ll. ln a telephone system, a party line, means individual to the party line controlled by digit inipulses for signalling any desired station on said party line, a connector having access to said party line, and means in the connector for transmitting digit impulses to said lirst-named means for operating the same to select a desired station on the party line.

12. In a party line telephone system`r a party selecting device individual to a party line, means 'l'or extending a connection from a calling line to said party line and l'er subsequently operating said selecting device to signal the desired called party on the line, means tor maintaining the called line busy to other connecting meansl until said selecting device is released, and circuit conncc tions etl'ective responsive to the tern'lination ol' the cmiversation by both ot the conversing parties for releasing said selecting device.

il. In a rotary connector switch, a stepping relay for controlling the automatic trunk limiting moven'ient ot the switch, a test. wiper, contacts controlled by the switch shalt responsive. to a predetermined movement ot the shaft, circuit connections controlled by said contacts in one position for controlling the stepping relay, and circuit connections controlled by said contacts in another position for establishing a digit impulsing circuit to said Wiper.

1l. In a. telephone system, a switch having access to lines extending to subscribers that have a plurality ot lines as well as to lines that have a plurality of subscribers thereon, all lines terminating in the same number of contacts at the switch, means responsive to the selection of a line of the lirst-mentiom-d kind by the switch for causing the switch to hunt lor and seize an idle one of the lines extending t0 the desired subscriber, and means individual to each party line etl'eetive if a party line is selected for .selectively sigmilling any desired party on the line.

In Witness whereof, I hereunto subscribe my name this twenty-ninth day of March, A. D., 192".

NORUAN Il. SAUNDERS.

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