Patent GB-194580-A (GB)
Title: Improvements in or relating to telephone systems
IPC: F16K31/26
Filed: 1922-04-21
Abstract: 194,580. Automatic Telephone Manufacturing Co., Ltd., (Assignees of Richardson, R. G., and Nelson, M. L.). March 29, 1922, [Convention date]. Addition to 193,694. Automatic exchange systems.-Relates to a system of the kind described in the parent Specification, in which the first three letters of the name of the wanted exchange are dialled to a register-control, which translates them into the series of digits necessary for routing the call to that exchange. According to the present invention the register-controllers are divided into ten groups, the first dialled letter being arranged to operate a group selector F, Fig. 8, to pick out an idle register-controller of a corresponding group, which then records the two other letters and the subscriber's number. By this arrangement each register-controller need comprise only one instead of nine two-co-ordinate exchange registers, and the distributing frame which forms part of the register-controller and which determines the translation of the exchange digits is of correspondingly smaller capacity. There may aetually be fewer than ten groups of register-controllers. For example, in the scheme shown in Fig. 8, exchanges commencing with I or P (first groups, Fig. 12) are merged with exchanges commencing with C, L or T (fourth group), the first and fourth levels of the switches F being multipled together. This is possible if there are no exchanges in the first group having the same second and third letters as an exchange in the fourth group. Again, there may be no exchanges commencing with G or X (eighth group) or with H or Y (ninth group), in which case the eighth and ninth levels of the switches Fare multipled together and give access to register-controllers IX which route the call to a " dead-number " operator. The tenth level gives access to register-controllers X which route the call to a toll operators' position LD at a central exchange. The register controllers IX, X, unlike those of other groups, send out an invariable series of digits and are therefore of a very simple type. The number of register-controllers provided in each group depends on the traffic. If there are more than ten register-controllers in a group they are connected to the banks of the switches F on the overlapping principle, or through non-numerical switches. Non-numerical switches may also be provided between the trunks C<2>, E<1> and the switches F. In a modified system, the group selectors Fare replaced by first, second and third group selectors, which respond to the three exchange letters and select a register-controller of a group individual to the wanted exchange. In this modification, which is not described in detail, the register-controllers are organized to send an invariable series of exchange digits followed by the wanted subscriber's number. A further feature of the invention consists in the fact that the register-controller is released after sending the exchange digits if at that moment the subscriber has not yet started to dial the wanted number, the digits subsequentlv dialled passing direct from the calling line to the wanted exchange. The following description refers to a system raid out as in Fig. 8, in which the brokenline rectangles represent an originating exchange and three out of the numerous other exchanges in the area. It will be observed that the exchange LOT is of the " tandem " type, that is to say the incoming selectors at this exchange give access over one level to local selectors and over other levels to lines leading to other exchanges. Selection of an idle register-controller of the group corresponding to the first called digit. The impulses of the first digit operate the line relay 64 of the switch F, Fig. 1. which operates like a group selector. The energization of the switching relay 68, when an idle register-controller of the proper group has been found, for example the register-controller shown in Figs. 2, 3, 4 and 5, grounds wire 102 to energize relays 110, 111. Fig. 3, and 210, Fig. 2, and closes a loop circuit 100, 101 across the trunk 20, 22. Registration of the remaining called digits. The next digit is repeated by relay 64 over circuits 103, 202, 218, 301 to the vertical magnet 303 of the exchange register J, Fig. 4. During the digit a relay 207, Fig. 2, in the impulse circuit energizes relay 208, so that at the termination of the digit an impulse is sent to magnet 212 to step the switch M to its second position. The next digit is therefore delivered to the rotary magnet 304, and the switch M is moved to its third position, and subsequent digits are delivered in a similar manner to the magnets 227, 226 &c. of the thousands, hundreds &c. registers M<1> - - M<4>. Transmission of exchange digits by the register-controller. As soon as the switch M moves to its third position, after the registration of the last exchange digit, it grounds the circuit 400, 405, 425 of the impulse relay 107, Fig. 3, which causes the rotation of the sending switch S and the generation of impulses in the trunk loop circuit 100, 101 as in the parent Specification. A branch of the grounded circuit 400 extends also through wiper 404, Fig. 5, and wire 411 to the wiper 306, Fig. 4, of the register J, and thence through one of the bus-bars 1 - - 9 of the distributing frame IDF to a corresponding terminal in the bank of the wiper 114 of the switch S. When the wiper 114 reaches the grounded terminal, i.e. when a number of impulses has been transmitted corresponding to the bus-bar picked out by the register wiper 306, relay 105 is energized and locks itself up, open-circuiting the impulse relay 107, completing a circuit 113, 116, 115 to step the switch S forward to normal, and opening a circuit 426, which was previously closed by an off-normal relay 106, so that magnet 402, Fig. 5, steps the auxiliary switch S<1> to its second position. On the return of the switch S to normal, relays 106, 105 successively and sluggisbly de-energize, so that after an interval sufficient for the hunting movement of the first selector E<1>, Fig. 1, the circuit of the impulse relay 107 is again completed and the transmission of the second digit commences. The number of impulses in this digit corresponds to the bus-bar picked out by the register wiper 307, Fig. 4, which is now grounded in the circuit 400, 404, 412. The transmission of further digits, up to a total of four, may be effected in similar manner, the different digits being transmitted in successive positions of the switch S<1>, and their individual values being determined by the busbars picked out by the four register wipers 306 - - 309. If less than four digits are required for routing the call to the wanted exchange, the register wipers that correspond to unwanted digits are arranged to pick out bus-bars X, Y, Z, which are wired to circuits 372, 371, 370 for moving the switch S' automatically through the corresponding unwanted positions. It will be noted that only nine numerical bus-bars are provided in the frame IDF. The tenth terminal in the bank of the sending-switch wiper 114 is grounded, so that ten impulses are sent unless one of the previous terminals has been energized. Consequently if ten impulses are required in any digit the terminal engaged by the corresponding wiper of the register J is merely left dead. Transmission of the remaining digits by the register controller. With the switch S' in its fifth position, ground is connected over circuit 415 to the wiper of the thousands register M<1>, and if, or as soon as, the setting of this register is completed, ground is connected over circuit 236, 235, 421, 405, 425 to the impulse relay 107, and the thousands digit is transmitted in a manner similar to the exchange digits. The hundreds, tens, and units digits are transmitted in succeeding positions of the switch S<1>, these operations being dependent on circuits 422, 423, 424 which are closed after the registers M<2>, M<3>, M<4> have been set, and the switch S' finally moves to its ninth position. Release of the register controller. A circuit 406, 420 is now closed to energize relay 112, Fig. 3, which locks itself up and energizes relay 13, Fig. 1, which switches the talking circuit through and disconnects relay 64. The circuits are arranged so that this operation shall be silent to the calling subscriber. The relapse of relay 65 energizes magnet 71 to release the switch F. This causes the de-energization of relays 110, 111, Fig. 3. Relay 111 grounds a circuit 160 for restoring the switch S' and relay 110 grounds a circuit 204 to energize the release magnets of the varjous registers. A relay 108 in this circuit grounds the wire 102 to mark the register-controller busy until the release operations are completed, and a relay 109 is energized for the same purpose until the switch S' is restored to normal. Premature release. In the case of premature abandonment of a call the relapse of relays 64, 65, Fig. 1, releases the switch F, and the release of the register-controller follows as already described. In this case, however, the sending switch S may be in an off-normal position at the moment of release. The relapse of relay 111 is therefore arranged to close a circuit 113, 132, 115 to restore it, and the relay 109 is kept energized until it regains its normal position. Signalling failure of register-controller to release properly. If any of the registers or the switch S or S<1> fails to restore itself, relay 108 or 109 remains energized, grounding the test-circuit 102 and an alarm circuit 498. Release of register-controller if the dialling of the call is interrupted or not completed. The. energization of relay 210, Fig. 2, when the register-controller is first seized connects a 30-second interrupter T to relay 205, which, at the next closure of circuit 299, locks itself up in series with relay 206, and the latter relay, which becomes energized only when the cam T br