US1944570A - Arrangement relating to automoatic telephone systems - Google Patents

Description

Jan. 23, 1934. A. H. oLsoN El' AL.

ARRANGEMENT RELATING TO AUTOMATIC TELEPHONE SYSTEMS Filed Nov. 5, 1932 4 Sheets-Sheet l Jan. 23, 1934. A H, OLSON E, AL 1,944,570

ARRANGEMENT RELATING TO AUTOMATIC TELEPHONE SYSTEMS 4 Sheets-Sheet 2 Filed NOV. 3, 1932 Axel Heimqn San 5+ Dam'cal Vlarem i NEN-roms 4 @Www um Jan. 23, 1934. A OLSON vE -r AL 1,944,570

ARRANGEMENT RELATING To AUTOMATIC TELEPHONE SYSTEMS Filed Nov. 3, 1952 4 Sheets-Sheet 3 lNvENToRf,

Jan. 23, 1934. A. H. OLSON ET AL 1,944,570

ARRANGEMENT RELATING TO AUTOMATIC TELEPHONE SYSTEMSl 1932 4 Sheets-Sheet 4 Filed Nov. 3?.

Patented Jan. 23, 1934 ARRANGEMENT RELATING TO AUTOMATIC TELEPHONE SYSTEMS Axel Herman Olson and Sten Daniel Vigren, Stockholm, Sweden Application November 3, 1932, Serial No. 640,975, and in Sweden November 20, 1931 Claims.

This invention relates to a certain new and useful arrangement for automatic telephone systems, and the following' is a full, clear and exact description of the same, reference being made to 5 the accompanying drawings, forming part of this specification.

Our invention has reference to an arrangement for automatic telephone systems, that makes possible an economic automatic switching between various telephone plants of different size and varying operating conditions.

Making rural telephone plants automatic has heretofore caused certain diiiiculties of economic and technical nature.

These difficulties have specially been observed in such systems, which contain several exchanges of diierent sizes, said systems being usually re ferred to as star shaped.

In such systems it is economically desirable to employ as few registers as possible and this is specially so in small rural exchanges that contain few subscribers. Furthermore, it is desirable,

when registers are employed in intermediate exchanges only, that they be used as little as possible.

The present invention has for its object an arrangement for automatic telephone systems, to permit economical automatic service between telephone plants of different kinds and comprising exchanges of various sizes.

The invention is principally characterized by the fact, that registers and so called exchange group selectors, that is, switching devices for selecting idle trunk lines to other exchanges, are located principally at exchanges which are arranged for tandem working and by the fact that the registers are used only for calls between two or more exchanges.

Another characteristic of the invention is that the exchange group selectors can be directly operated by impulses from a register. The exchange group selectors can, however, also be so arranged, that they are operated by impulses from registers via direction selectors.

The necessary direction selectors are arranged for selection over two separate groups of lines, of which one is used for direct connection to necessary group and line selectors for internal traffic and the other for direct connection to exchange group selectors. The direction selectors are so arranged that the sequence in which its groups of lines shall be selected. can be changed by changing the connections of the direc 55y tion selector.

The advantages of arrangement the invention are manifold:

according to In order to establish a connection between subscribers connected to the same exchange, only that number of digits need be dialled which corresponds to the size of that exchange, that is,

the number of the subscriber.

If a communication is desired between subscribers connected to different exchanges, that number of digits should be dialled, which depends partly upon the exchange of the desired subscriber and the size of said exchange.

partly upon Another advantage of the invention isthat it permits so-called cross connections of star shaped plants, that is, direct connections from one exchange to another, should the `exchanges belohg to the same or to diiierent districts. Existing plants can thus be used and the lines needed for a certain connection can be made shorter than is now the case in star shaped plants.

The cross connections are of the greatest importance in cases where, for instance, 'a terminal exchange, a satellite to a larger exchange or so-called junction exchange, has a heavy traiiic with other terminal or junction exchanges. In such cases it is economically desirable to establish direct lines so-called cross trac between two. nearby exchanges belongingY connections. Heretofore,

to different districts, has been directed over the respective district exchanges. With cross connections, according to the present invention such roundabout ways are avoided. v

This invention provides for a simple time-Q zone-metering. When a register has accumulated a number corresponding to a certain exchange, said exchange lis definitely determined, Whereby circuits for toll charges devices can be prepared for completion, when the communication is established.

The invention is further characterized by the fact that a call lfrom oneexchange to another is accumulated in a register which in any known way transfers and transmits the impulses corresponding to the desired number. When the for traic change.

:to a subscriberbelonging to the ex Civ.

Fig. 1 4. show difieren The arrangement of direction selectors and exchange group selectors in series has advantage that group and line selectors oi an exchange will be used not for tandem working to other exchanges, but only for internal connections between subscribers belonging to the same exchange. In axchanges having relatively heavy outgoing traflic this arrangement makes it possible to build the selecting equipment at a lower total cost than what would be possible with arrangements with exchange group selectors without direction nnders.

Even in cases, where the exchange group selectors are used for internal as well as for outgoing and through traiilc, the register devices will be occupied only for communications via two or more exchanges. The selectors and the registers are thereiore arranged in such a way, that communications are obtained over one or more exchanges, no matter where situated, by dialling the number of the desired subscriber, or a direction number. A tone is received from the register corresponding to the last exchange number and the number of the desired subscriber. The connection or" the registers ior receiving and transmitting dial impulses is such, that the register is controlled by group selectors or so-called exchange group selectors. The latter are of such a construction, that they are used only by establishing communications via one or several exchanges. Should the communication be extended only over one exchange, the exchange group selectors will be used only once.

Should the communication be extended via two or several exchanges, the exchange group selectors will be used twice. By dialling a so-called direction number, the exchange group selectors are connected to a register and eventually over register selectors in such a way that the exchange group selectors will again be restored to normal position, and then operated by the rst series of impulses transmitted from the registers after the transmission of the dial tone. The connection to registers and register selectors is cut off after the transmission of all impulses from the corresponding register.

Other characteristics of the invention will appear from the following description in conjunction with the accompanying drawings, of A'which arrangements according to thel invention. Although the automatic system is disclosed as applied to cross-oar switches, which can be used as line finders, direction selectors, line selectors, exchange group selectors, register selectors,k registers, etc., it can be used also in combination with other types of switches. When a terminal exchange with step-by-step selectors is connected to a system according to this invention, no changes are necessary in such a terminal exchange.

One of the principal advantages of the system according to this invention is `that trunks or junction lines, selectors and registers are not made busy before they are really needed for es= tablishing a connection. The dial impulses op erate the selectors directly as long as such a proceeding is desirable and suitable to a uniform numbering scheme. Registers are introduced only when really needed, that is, when a call The first cost will be reduced to a minimum.

Fig. 1 shows the arrangement, according to which the transmission of impulses from registers is directedl via direction selectors to* .ex-. change group selectors, etc., while Fig. 2 shows exchange group selectors directly connected to register connecting devices or register preselectors and by which arrangement direction selectors will be less used, than according to the arrangement shown in Fig. 1. Figs. 3 and 4 show special forms of arrangements according t0 Fig. 2. In Fig. l K13, E19, Kzi and D22 are provided with direction selectors in addition to the exchange group selectors, only exchange Kw being provided with the latter. This ngure is intended to show the flexibility of the system, satisfying different individual traffic requirements oi each exchange.

In Fig. 2 there are no direction selectors of K13, Kao, Km, D22.

The exchange group selectors are in both cases so arranged that they can be operated directly by impulses transmitted from a register or by the impulses of a subscribers dial.

According to Fig. 2 a substantial reduction of the number of direction selectors of the whole system is obtained and is specially suitable for the mechanization of existing rural telephone plants.

The exchange group selectors can be connected directly to direction selectors as per Fig. 1, or to a register via register selector as per Fig. 2.

Fig. l contains a number oi circles of which A10, ein, A17 represent lterminal exchanges. Kia, Kia, Kei intermediate or junction exchanges, and i322 a district or debiting exchange. The exchanges are provided with iinders, direction selectors, line selectors, register selectors, registers and exchange group selectors, which are marked S, lV, LV7 ReV and SGV respectively. The junction exchanges Kia, Kan and lszi are provided .with direction selectors and exchange group selectors for through traiiic, while the junction exchange Km is provided with only exchange group selectors for both through traiiic and tramo to subscribers connected to the said junction exchange. y

II" the subscriber 12 of the terminal exchange Aie calls another subscriber 20 of the same exchange, the subscriber 12 obtains a connection to the line selector LV1() over a iinder or preselector Sie, a direction selector RVio and eventually also over a group selector. The desired connection is obtained by dialling the number ai) of the desired subscriber. Ii the same subscriber l2 desires a connection to a subscriber 93 of the junction exchange Kia, he will obtain in the above described way a connection to a line selector LV 1o. l-aving received a dial tone he dials a special digit,

for instance 0. Y The direction selector RVN) will i be operated so that the connection to the group and line selectors of the terminal Vexchange A10 will be cut off and the connectionestablished over the contact l to an outgoing trunk line. When the call arrives to the junction exchange lire if over the contact 2, the subscriber l2 will automatically kobtain connection over a register selector RcVi to a register R18. 1i the said register is disengaged, the subscriber will receive a dial tone, aiter which he then may dial the numbers of both the junction exchange and oi' the desired subscriber, in this case 18-93.

rThe register R18 is so connected, that its transmitting device, after the dialling of the figures, first will transmit a series of impulses which will switch the direction selector RVH; from the conn nection to the exchange group selector SGViS to the group and line selectors LVN. The other impulses transmitted from the register are sent in any known way. Y

Should' the subscriber 1'2 desire to call the subscriber 3075 of the district exchange D22, the switching, in order to obtain connection to the register R18, will be similar to that described above. Upon receiving the dial tone, the subscriber l2 shall dial the numbers corresponding to the district exchange and to the desired subscriber, in this case 22-3075. In this case the register R18 will be connected in such a way, that its transmitting device, when the digits have been dialled, firstly transmits a series of impulses, which operates the exchange group selector SGV18 in order to iind a disengaged trunkline to the district exchange D22, whereby the contact 3 is closed. The next series of impulses operates the direction selector RV22 in order to connect it to the group and line selector LV22 of the district exchange. The following impulses transmitted from the register will complete the connection in any known Way.

If the subscriber 12 desires to call the subscriber 77 of the terminal exchange A17, the connection to the register R18 Will be similar to that described above. After receiving the dial tone, the subscriber 12 dials the numbers corresponding to the terminal exchange A17, and to the desired subscriber, in this case l7-77. The reg.

ister R18 is connected in such a way, that its transmitting device, after dialling, firstly will transmit a series of impulses, to operate the exchange group selector SGV18 to find a disengaged trunk line leading to the district exchange D22, whereupon the contact 3 is closed. The next series of impulses operates the exchange group selector SGV22 to find a disengaged trunk to the junction exchange K21, whereupon the contact 6 is closed. The following series of impulses operates the exchange group selector SGV21, to iind a disengaged trunk line to the terminal exchange A17,

whereupon the contact 7 is closed. Other transmitted series of impulses Will complete the connection to the subscriber 77 in any known way.

If a subscriber 25 of the terminal exchange A18 should desire to call the subscriber '77 of the terminal exchange A17, the dialling of the subscriber 25 will be similar to that which will take place, when the subscriber 12 obtains connection to the subscriber 77, although the connection will be established over a less number of exchanges.

In order to establish a connection between the subscribers 12 and 44 of the terminal exchange A10 and of the terminal exchange A14, respectively, the numbers of both the terminal exchange and of the desired subscriber must be dialled, in this case 14-44, whereupon a connection to the register R18 is obtained and dial tone is received. The register R18 is connected in such a way, that its transmission device, after dialling of the numbers, first transmits a series of impulses which operates the exchange group selector SGV18 to find a disengaged and direct trunk line to the terminal exchange A14. Other impulses transmitted by the register transmission device will complete the connection in any known way.

Ii a subscriber of a junction or of a district exchange, for instance the subscriber 88 of the junction exchange K18 desires to call the subscriber 93 of the same exchange, the calling subscriber 88 iirstly obtains connection to the line f selector LV18 over a iinder or preselector S18 and eventually also over a group selector. After receiving the dial tone, the number of the desired subscriber is dialled, whereupon the connection will be established.

Should the same subscriber 88y desire tocall another subscriber belonging to any other exchange, the subscriber 88, having obtained connection to a disengaged line selector` LV18 and having received the dial tone, must dial a special digit, for instance 0. The direction selector RVH;` will be operated in such a way, that connections will be obtained both to the exchange group selector SGVia and to the register R18 over the register selector ReV18.

Having received a dial tone the subscriber 88 will dial the numbers of both the exchange and the subscriber and these will be accumulated in the register. The switching arrangements are in other respects similar to those described above.

Fig. 2 also shows a number of exchanges marked by circles. A10, A11, A17 are terminal exchanges, K18, Kw, K21 junction exchanges and D22 a district ordebiting exchange. The terminal exchanges are provided with finders S, direction selectors RV and line selectors LV and the junction and the district exchanges with iinders S, line selectors LV exchange group selectors SGV, register selectors RcV and registers R. If necessary all exchanges can, of course, be provided with preselectors and group selectors.

Calls between two subscribers belonging to the same exchange, for instance to the terminal exchange A10, will be established in the same Way as described in conjunction with the arrangements, shown in Fig. 1.

However, in case of calls between two subscribers belonging to different exchanges of the same. district or junction exchange, the connection Will be different.

Ii in the arrangement according to Fig. 2' the subscriber 10 at the terminal exchange A10 de# sires a communication with a subscriber 393 of the junction exchange K18, hel obtains in the above described way connection to the line selec-- After receiving the dial tone, he dials fi tor LV10. a special digit for instance 0. The direction selector RV10 will be operated in such a manner that the connection to a group and line selector or" the terminal exchange is cut off, and connection to an outgoing trunk line over the contact 1 is obtained. When the callarrives'at the junction exchange K18 over ,the contact 2, the subscriber 10 is automatically connected over a reg.- ister selector ReVis to a register R18. If the register is disengaged, dial tone is sent out. The subscriber 10 then dials theY numbers of both the junction exchange and the desired subscriber, in this case 18393. The register R18 is so connected that its transmitting device, after theV dialling vof the digits, transmits a series of impulses, which operates the exchange group selectorSGVw, con-A necting it to group or line selectors LV18.. Other series of impulses complete the connection in the known way. v

Should the subscriber 10 of terminal exchange A10 desire to call the subscriber 3075 of the district exchange D22, the connection to the register R18 will be similar to that described above. After receiving the dial tone, the subscriber' 10 dials the numbers of both the district exchange andthe desired subscriber, in this case 22-3075. Ther-V register R1a is so connected that its transmitting.` device, after receiving the dialled numbers; first transmitsy a series of impulses which operates the exchange group selector SGV18 to iind a disen gaged trunk line to the districtf exchange D22,V

whereuponthecontactisclosed. The next series of impulses operates the exchange g-roupr selector,

SGV22 for connection` to the group or line selector LV22fvof the districtexchange.- Other-series of im'` 1 Eil? pulses, transmitted from the register, will complete the connection.

vIf the subscriber l() of the terminal exchange A111 desires to call the subscriber 77 of the terminal exchange A17 the connection to the register R18 will be similar to what has been described above. After receiving the dial tone the subscriber 10 dials the numbers of both the terminal exchange and of the desired subscriber, in this case 1'7-77. The register R18 is so connected that its transmitting device, after receiving the dialled nurnbers, rst transmits a series of impulses to operate the exchange group selector SGV18 to nnd a disengaged trunk line to the district exchange D22, whereupon the contact 3 is closed. The

'next series or impulses operates vthe exchange group selector SGVzz to nd a disengaged trunk line to the junction exchange K21, whereupon the contact 5 is closed.

The following series of impulses operates the exchange group selector SGN/21 to find a disengaged trunk line to the terminal exchange A17, whereupon the contact 7 is closed. Other series of impulses transmitted from the register complete the connection to the subscriber 77.

Ii' the subscriber 25 of the terminal exchange A16 desires to call the subscriber 77 of the terminal exchange A17, the connections will be similar to those which will take place when the subscriber l0 establishes a connection to the subscriber 77, although the connection will pass through a lesser number of exchanges.

In order to obtain a connection between the subscriber 10 and the subscriber 44 of the terminal exchange A14, the numbers of the terminal exchange A14 and that of the desired subscriber must be dialled, in this case lli-44 after connection has been made to the register and the dial tone has been obtained. The register R18 is so connected that its transmitting device, after receiving the dialled numerals, first transmits a series of impulses to operate the exchange group selector SGV18 to find a disengaged trunk line going directly to the terminal exchange A14. Other transmitted series of impulses complete the connection in any known way.

If a subscriber oi a junction or district exchange, for instance the subscriber 288 of the junction exchange K11; desires communication with subscriber 393 of the same exchange, the calling subscriber 288 obtains connection to exchange group selector SGVw over a finder or preselector S13. Having received a dial tone he dials the number of the desired subscriber, whereupon the connection is obtained in any known way.

Should the same subscriber 288`desire to call another subscriber belonging to any other exchange, the subscriber 288, after having established connection to the exchange group selector SGVis, dials a special digit, for instance 0. In this Way connection is obtained to a register R18 over a register selector ReVm. Having received a dial tone, the subscriber 288 dials the numbers of the exchange and of the subscriber. These numbers are accumulated in the register. The switching arrangements are in other respects similar to those described above.

Figs. 3 and e show diagrammatically an exchange group selector circuit according to the system shown in Fig. 2.

The constuction and the connection of the registers and register selectors will be alike and independent of the origin and destination of the calls as will be clearfrom the following. The

b. Calls extended over two or more exchange group selectors.

c. Calls extended over a direction selector and one or several exchange group selectors.

a. Calls extended over only one exchange group selector When for instance the subscriber 288 belonging to junction exchange K13 desires to call the subscriber 393 belonging to the same exchange, the first subscriber lifts his receiver from the hook whereupon he obtains connection to the exchange group selector SGV over a finder or preselector and the line L (see Fig. 4) over contacts 4 and 7 of relay R1 in the register selector ReV (see Fig. 3).

R10 (Fig. 4) is operated (plus, operating winding of R10, 1R11, conductor a, LiR1, the loop of the subscriber, VH1, conductor b, 3R11, lower Winding of R10, minus). The operation of R10 breaks the contacts 2, 3R10 and closes 1R10 in such a manner that. R11 and R12 are operated in parallel. The circuit or" R11 passes from plus over 1R10, R11 to minus, and that of R12 from plus over 1R10, 2R13, R12 to minus. The operation of R11 opens the Contact 3R11 and closes l, 2, i, 5, 6 and 7R11. The closing of 4R11 causes the operation of cut oli relay oi the calling subscriber and busies the corresponding iinder and preselector. The closing oi l, 2R11 makes possible the transmission ci dial tone from the buzzer devices SU (SU, 1R13, iR11, the buzzer winding of R10, 2R11, SUj. The buzzer tone is transformed over the operating winding of R10 and the wires d and b to the subscriber.

The subscriber after receiving dial tone will dial a special direction digit, for instance 0, if he desires to call a subscriber connected to another exchange. In order to explain the operations that occur, when the subscriber, after receiving dial tone, dials the digit 8 (one impulse), the switching operations at the begining and at the end of the impulse will be described.

1st impulse starts-R10 is demagnetized on account of the opening of the impulse contact of the subscribers dial. STB/i0 (Fig. 9) is energized (plus, 2R10, 5R11, 1R12, 3R15, STlVio, minus), whereby 1, 2, fiSTMo are ciosed and BSTMO is opened. The closing ci 2STM0 inagnetizes R13 (plus, 5R11, R13, 4R13, 2STM11, minus), which receives holding current (plus, 6R11, R13, 5R13, minus). When R13 is energized l, 2, 3, 4R13 are opened and 5, 6R13 are closed. The buzzer SU is disconnected.

1st impulse ceases.-R10 is magnetized, when the impulse contact ci the subscribers dial is closed, STM@ receives holdingY current in series with R14, which is magnetized (plus, 6R11, 8R13, 4R14, R14, STT/11, 4STMO, SThc, minus) At the end of the iirst impulse R10, R11, R12, R13, R14 and STM@ are niagnetized, R12 on account of its delayed action. As the impulse'series now is ended, R12 will be de-energized when the time of delayed action is over. '2R12 is closed, whereby the bar magnet STM1 is magnetized (plus, STD/i1, lORi, d-Wle, 2R12, 3R14, ZSTD/i'o, minus) and 1, 2STM1 are closed.

The hunting for a disengaged trunk from the register selector to a register', is started, HBRlVi1 is magnetized (plus, HBRMi, 4HBRM2, 4HBRM3, 1STM1, minus), whereby 3, 5HBRM1 are closed and 2HBRM1 is opened. The closing of 5HBRM1 causes the testing relay R7 to be magnetized, if the first trunk from the register selector RdV to a register is disengaged (plus, 2STM1,R1, SHBRMg, 8HBRM2, 5HBRM1, contact corresponding to 1R5, minus). 1, 3R7 are opened and 2R7 is closed whereby R6 is magnetized (plus, Re, 2R7, ISTMO, minus), whereby 1R11 is opened and 2R11 is closed. Re thus receives holding current (plus, Re, 2Re, 1STM1, minus), and the hunting for a disengaged outgoing trunk ceases. BRD/I1 is magnetized (plus, BRM1, 3HBRM1, 6HBR1VI2, 2Ra, 1STM1, minus), and 3, 4, 5, 6, 7STM1 are closed. The closing of 7STM1 magnetizes a relay corresponding to R4 (plus, R4, 7STM1, 11R1, cl-wire, 2R12, 3R14, ZSTMU, minus). A contact corresponding to lRi is closed, so that a relay corresponding to R5 is magnetized and closes two contacts corresponding to 2, SRs. Rv is demagnetized and closes 3R11, so that R1 is magnetized. Its circuit will then be as follows (plus, contact corresponding to 2R11, 1BRM1, holding winding of BRD/I1, 5STM1, R1, 2R1, 3R? and minus). 1, 3, 5, 5, 8, 9R are closed and 2, 4, '7, l0, 11R1 are opened, whereby R1 receives holding current (plus, contact corresponding to 2Rs, 1BRM1, holding winding of BRD/I1, 5STM1, R1, 1R1, minus). The calling line L is connected to the register R. The opening of 4, 7R1 demagnetizes R10 of the exchange group selector, whereby all its corresponding relays are demagnetized. The closing of 3, SR1 causes that the wires u and b or" the calling line L to obtain feeding current over 6, '7STM1 from a relay corresponding to R11. The opening of 11R1 demagnetizes HBRM1. When a subscriber thus, after dialing the digit 0, has obtained connection to a disengaged register over a register selector, BRM1, R1 and two relays corresponding to V,R4 and R5 are the only relays, that remain magnetized.

Should the first line outgoing from the register selector ReV be engaged, R7 cannot be magnetized, 1R7 remains closed in this case, whereby HBRM2 is magnetized and opens the circuit of HBRM1. Should also the second outgoing line be engaged, HBRM3 is then magnetized, etc. Should all outgoing lines be occupied, HBRMs connects HBRM1, whereupon the hunting starts again.

From the foregoing it will be clear that, when a line L is connected to a disengaged register, one BRM relay and two relays corresponding to R4 and R5 are the only ones that remain energized. The closing of 9R1 busies the previously used eX- change group selector SGV, because plus is connected to its c-wire.

For the sake of nsimplicity let us assume that BRD/I3 is magnetizd instead oi BRD/I1. The line L thus obtains its feeding current from the re lay R4 over the contacts 16, i'lSTM1. rThe closing of 1R4 magnetizes R5 (plus, 1R11, R5, minus), whereby SRs is closed and buzzer tone is transformed to R4 and the line L. Having received a second dial tone the subscriber dials the numbers of the exchange and of the subscriber, which are accumulated in the register to be retransmitted later. Before the transmission device of the register transmits the impulses necessary for the setting of the diiierent selectors, lRs is closed. This happens after the subscriber has dialled one or several digits and causes R2 to be connected to the wires a and b attached to the exchange group selector SGV over 13, 14STM1 and 5, 8R1. When the series of impulses from the register are transmitted, 1R2 is closed and opened in the same way as the impulse contact of the vdial of the calling subscriber. In order to understand the switching arrangements of the exchange group selector those conditions can for instance be studied, which take place when the impulse transmitting device of the register transmits the iirst series of impulses. This'series corresponds for instance to the digit 2 (3 impulses). In order to understand the switching it will be convenient to study the conditions at the beginning and the end of each impulse.

The 4first impulse starts-R10 is demagnetized on account of the opening of the impulse contact 1R2. STMO is rnagnetizedv (plus, 2R10, 5R11, 1R12, 3R13, STMO, minus), whereby 1, 2, A4STM0 are closed and SSTMQ is opened. The closing of ZSTMO magnetizes R13 (plus, 6R11, R13, 4R13, 2STM0, minus), which receives holding current (plus, 6R11, R13, 5R13, minus). By the magnetizing of R13, l, 2, 3, 4R13 are opened and 5, SR13 closed. The buzzer SU is disconnected.

The first impulse ceases-R10 is magnetized by the closing of 1R2. S'IMo receives holding current in series with R14 whichv ismagnetized (plus, 6R11, BRS, 4R14, R14, 1STE/I1, 4ST1\40,'STM0, minus) When the rst impulse ceases, R10, R11, R12, R13, R14 and S'IMo are magnetized, R12 on account of its delayed action.

The second impulse starts-R10 is demagnetized on account of the opening `of thefimpulse contact 1R2. STM1 is magnetized (plus, 2R10, 5R11, 1R12, 2R14, ISTMO, STM1, minus), whereby l, 2, BSTR/ f1 are closed and 4STM1 is opened. The opening of 4STM1, however, does not demagnetize R11, because this relay has holding current (plus, 6R11, TR2, 3R10, 5R14, minus). STMo is, however, demagnetized upon the opening of 4STM1.

The second impulse ceases- R10 is magnetized upon the closing of 1R2, whereby 1R10 is closed and 2, 3R10 are opened. The opening of 3R10 demagnetizes R14, whereby 1, 4, 6R14 are closed and 2, 3, 5R14 are opened. STM1 gets holding current over (plus, 6R11, SRs, 3STM2, 2S'I'M1, STM1, minus).

After the end of the second impulse R10, R11, R12, R13 and STM1 are magnetized, R12 on account of its delayed action.

The third impulse starts-R10 is demagnetized on account of the opening of the impulse contact 1R2. STM2 is magnetized (plus, 2R10, 5R11,

1R12, 1R14, 1sTM2,. 11111111s whereby 1, 2, 4sTM-2 'i are closed and 3STM2 is opened. VThe opening of 3STM1 demagnetizes STM1.

The third impulse ceuses.-R1o is magnetized upon the closing of 1R2. STM2 receives holding current in series with R14, which is magnetized (plus, 6R11, 8R13, 4R14, R14, 4STM3, 4STM2 minus) When the third impulse ceases, R10, R11, R12, R13, R14 and STM2 are thus magnetized, R12 on account of its delayed action.

When the series of impulses have been sent out, R12 is demagnetized after the time of the delayed action, whereby 1R12 is opened and 2, 3R12 are closed. The closing of 3R12 magnetizes BRM and l, 2, 3STM2 are closed. If the first outgoing line is disengaged, R9 is magnetized, before BRM2 gets time to operate. The circuit of R9 will be (plus, 6R11, R9, 7R11, lBRMa, 1BRM2, 1STM2, the outgoing c-wire not shown, minus). The magnetizing of R9 opens 1, 3R9 and closes 2R11, By opening of IRQ, BRM2 is prevented from magnetizing. The closing of 2R9 causes Ra to be magnetized (plus, 6R11, ZRQ, Re, min-us), whereby 1, 3, 5, 7, 8, 10H8 are opened and2, 4, 6, 9, llRs are closed. The closing of 2, 4R8 causes the incoming a and b wires to be connected to the corresponding outgoing ones over 3, 2STM2. The closing of SRS connects ground to the incoming c-wire, whereby the group selector is busied. The opening of 7, SRS demagnetizes R14. The closing of QRS causes holding of R8 (plus, 9R15, 2R9, Ra, minus). The opening of 1, SRS demagnetizes R10, whereby R11 is demagnetized and opens 6, 7R11, whereby also R13 and R9 are also demagnetized. R9 gets holding current from the succeeding selectors c-wire, which in the meantime has been connected to ground (plus, c-wire, ISTR/I2, 1BRM2, lBRMs, 3R9, llRs, Rs, minus). When the connection has been established, Ra and BRM1 are the only relays of exchange group selector SGV that are magnetized.

After the exchange group selector has been operated by the' iirst series of impulses transmitted from the register, the other series of impulses are transmitted, which will operate the succeeding selector. As soon as the last two series of impulses have operated a line selector, the circuit of R1 is automatically opened and R1 is demagnetized, whereby the register selector ReV and also the register are disconnected and the Awires a and b of the line L are connected to the wires a and b leading to the exchange group selector SGV.

As will be noticed from the above description, an impulse can be transmitted also from the register to connect those from the exchange group selector SGV, which correspond to the STM() magnet.

b. Calls extended over two or more exchange group selectors When, for instance, the subscriber 288 belonging to the junction exchange K11; calls the subscriber 3075 of the district exchange D22, the switching will in general be similar to what has been described under a.

When the first impulse transmitted from the engaged register, has caused connection to a line leading to the district exchange D22, the contact 3 is operated when that line is tested and formed, disengaged, whereupon connection is obtained to an exchange `group selector of district exchange D22. Said exchange group selector can not be connected to a register. Buzzer arrangement is not needed either. Accordingly the arrangements of Fig. l for transforming buzzer tone and the d-wire are unnecessary at exchange group selectors which are used by a call from a preceding exchange group selector. r1`he switching is otherwise similar to that described above.

c. Calls extended over a, direction selector cmd one or several echcmge group selectors When, for instance, the subscriber 10, belonging to the terminal exchange A10, calls the subscriber 393 of the junction exchange Km, the switching will be as follows: When the subscriber 1G lifts his telephone and is connected over nder S10 and a preselector and direction selector RVm to the line selector LV10, dial tone is transmitted. The subscriber dials the digit 0, whereby the direction selector RV10 is connected to a trunk leading to the junction exchange when this line is tested and found disengaged, contact 1 is operated establishing a connection to an exchange group selector. In this case a second dial tone will be transmitted direct from a register and not from the selected exchange group selector, that is, connection to a register over a register selector will be obtained automatically as soon as connection to an exchange group selector has been obtained. The minus pole is connected to the Contact 1R11 and the contact 1R13 is connected to the d-wire. As the dial tone buzzer of the exchange group selector does not function, it is disconnected. The switching is otherwise similar to that described above under a.

It will be clear that the invention can be modiiied in several ways without departing from the main idea. Thus, for instance, in the terminal exchanges shown, direction selectors RV may be replaced by group selectors of the same construction as the exchange group selectors SGV.

It will also be clear'that connections can be extended over any number of exchanges in series with registers provided only in even number exchanges, counted from the terminal exchange.

Having thus described our invention, what we claim is: y

l. In an automatic telephone system, a plurality of full automatic terminal exchanges, and a plurality of iull automatic intermediate exchanges, direction selectors in said terminal exchanges, impulse accumulating and transmitting registers at said intermediate exchanges only, subscribers lines terminating at said exchanges, impulse transmitting dials associated with each v one of saidV lines, and means controlled from said terminal exchanges for actuating said registers to establish connections between a plurality of exchanges.

2. ln an automatic telephone exchange system according to claim 1, characterized by exchange group selectors in said intermediate exchanges, means responsive to the dialling of the number of a called subscriber belonging to the same exchange as the calling subscriber for establishing a connection with this line, means responsive to the dialling of a direction digit by a line for operatinga said direction selector to connect with 12@ a register, and means responsive to the dialling of a number of the called subscriber belonging to a different exchange than the calling subscriber for operating said register to establish a connection to said called subscriber at said diiferent exchange.

3. In an automatic telephone exchange system, a plurality of full automatic terminal exchanges, a plurality of full automatic intermediate exchanges, subscribers lines terminating in said exchanges, impulse transmitting dials associated with each one of said lines, impulse registers and exchange group selectors in said intermediate exchanges, means controlled by the dialling of a calling subscriber for operating said registers, means controlled by said reters for operating said exchange group selectors, and means controlled by the dial of a calling subscriber for operating said exchange group selectors.

4. In an automatic telephone system, a plu- 14o rality of full automatic terminalexchanges, a plurality of full automatic intermediate exchanges, subscribers lines terminating at said exchanges, impulse transmitting dials associated with. each one of said lines, impulse registers and exchange group selectors at said intermediate exchanges, means controlled by said dials for operating said registers, means'controlled by said dials for operating said exchange group selectors, and means responsive to the operation of said exchange group selector for connecting a calling line with said registers.

5. In an automatic telephone exchange system, a plurality of full automatic telephone exchanges, a plurality of full automatic intermediate exchang-es, subscribers lines terminating in said exchanges, impulse transmitting dials associated with each one of said subscribers lines, impulse registers and exchange group selectors at said intermediate exchanges, means controlled by said dials for operating exchange group selectors, means controlled by said registers for operating exchange group selectors, and means responsive to the dialling of a certain digit by a subscriber belonging to an intermediate exchange for connecting with the calling subscribers line said registers.

6. In a telephone exchange system, a plurality of full automatic terminal exchanges, a plurality of full automatic intermediate exchanges, subscribers lines terminating at said exchanges, impulse transmitting dials associated with each one of said lines, exchange group selectors at said intermediate exchanges, means for establishing a connection over said group selectors between a calling and a called subscriber belonging to an intermediate exchange, and means for establishing a connection through said group selectors between a calling subscriber belonging to an intermediate exchange and a called subscriber belonging to a different exchange.

7. In a telephone exchange system, a plurality of full automatic terminal and intermediate exchanges, a plurality of lines terminating at said exchanges, impulse transmitting dials connected with each one of said lines, exchange group selectors at said intermediate exchanges, means controlled by the dial of a calling subscriber belonging to an exchange for once operating a group selector to establish a connection with a called subscriber belonging to the same exchange, and means responsive to the operation of the dial of a calling subscriber belonging to one exchange for twice operating said group selector to establish connection with a called subscriber belonging to a different exchange.

8. In a telephone exchange system, a plurality of full automatic terminal exchanges, a plurality of full automatic intermediate exchanges, a plurality of subscribers lines terminating at said exchanges, impulse transmitting dials associated with each one of said lines, exchange group selectors and impulse registers at said intermediate exchanges, means responsive to the dialling of a direction digit by a subscriber belonging to any exchange to operate a group selector to connect the calling line with a register, means operative thereupon for restoring to normal the operated group selector, means controlled by said register for actuating said last mentioned group selecto-r, and means for disconnecting said register from the last mentioned group selector.

9. In an automatic telephone system, a plurality of full automatic terminal exchanges, a plurality of full automatic intermediate exchanges, a plurality of subscribers lines terminating at said exchanges, an impulse transmitting dial associated with each line, exchange group selectors and impulse registers at said intermediate exchanges, means for connecting a calling line at one exchange with a distant intermediate exchange, means operative thereupon for actuating said exchange group selectors to connect the calling line at said registers, and means responsive to the dialling of a direction digit by another calling subscriber for actuating said exchange group selectors for connecting the last mentioned calling line with said registers.

10. In an automatic telephone system, a plurality of terminal exchanges, a plurality of intermediate exchanges, subscribers lines terminating at said exchanges, a calling dial associated with each line, selector switches at each exchange, impulse accumulating and transmitting registers at said intermediate exchanges only, means responsive to the dialling of the number of a called line belonging to the same exchange as the calling line for operating selectors to interconnect said lines without the intervention of said registers, and means operative upon the dialling of the number of the called line belonging to a different exchange for iirst connecting the calling line with a register and then actuating said register to operate selectors for extending the connection to the called line, the dialling number of the last mentioned called line consisting of a number designating the register, a number designating the called oice and a number designating the called line proper.

AXEL HERMAN OLSON. STEN DANIEL VIGREN.

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