Patent GB-193694-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/00
Filed: 1922-03-08
Abstract: 193,694. Automatic Telephone Manufacturing Co., Ltd., (Assignees of Richardson, R. G., and Nelson, M. L.). Feb. 23,1922, [Convention date]. Automatic exchange systems.-In a system comprising a large network of exchanges, a call is made by dialling the first three letters of the name of the wanted exchange followed by the four-digit number of the wanted subscriber, the whole seven-digit designation being recorded on a register-controller which translates the three exchange digits into a series of two, three or four digits representing the position of the wanted exchange relatively to the calling exchange in the general trunking scheme. The four final digits are re-transmitted by the register-controller without modification. The subscribers' dials are lettered and numbered as shown in Fig. 12. Subscriber No. 2345 in the exchange. " Carlton," for example, would be listed in the directory as CARlton 2345. The letters CAR correspond to digits 422, of which the first operates a register M<2>, Fig. 6, to pick out one of nine two-co-ordinate registers H<1>, Fig. 7, which is operated by the other two digits to set its wipers 220 - - 223 on a set of terminals wired to contacts 257 - - 254, individual to the exchange Carlton, at the left side of a distributing frame IDF. These contacts are jumpered to bus-bars at the right side of the frame in a manner corresponding to the digits that must be transmitted To extend the connection to the Carlton exchange. For example, if the digits 34 must be transmitted for this purpose, contact 257 is jumpered to bus-bar 3 and contact 256 to bus-bar 4, while contacts 255, 254 are jumpered to blank bus-bars 271, 270. The bus-bars 1 - - 10 are wired to terminals of an impulse sending switch S', Fig. 8. The registercontroller comprises means for steering the connection to toll and complaint operators, &c., in response to particular digits, or in case the dialling of the number is not completed. Means are provided for delaying the hunting of a group selector in case all the trunks in the selected level are busy. Connection to idle register-controller. When a line switch C seizes a first selector trunk D, E',. the finding switch F of the first idle register con. troller is set in action by the energization of relay 86 over a starting circuit 78 and hunts until it finds the terminal 101 from which ground has been removed by relay 51, whereupon relay 85 becomes energized and transfers the starting circuit to the next idle finder. Relay 85 also locks itself, energizes relay 52 to open the starting-circuit, grounds the terminal 101, energizes relay 142, Fig. 6, in a circuit 133, 77, prepares an impulse repeating circuit 75, 134, and bridges a polarized relay 375, Fig. 8, in a loop circuit 136, 137, 79, 80 across the selector trunk 82, 83. Relay 375 energizes relay 378, which locks itself to the grounded wire 135. Registration of wanted number. Dialling tone is now transmitted from a machine Q, Fig. 6, over a circuit 157, 134, 75, k to the calling subscriber, who sends the seven digits. The impulses of the first digit are repeated over the circuit 75, 134, 157 to the magnet 155 which operates the register M<2> to pick out one of the nine two-co-ordinate registers H'. A slow-release series relay 140 is energized as long as impulses pass and energizes relay 141, and then relapses and transmits an impulse to magnet 153, to step the switch M<1> to its second position. A relay 143 is energized in parallel with magnet 153 and locks itself to the grounded wire 133. The second digit is repeated over the circuit 157, 170, 176 to the vertical magnet 214 of the selected register H' and the third digit to the rotary magnet 215. The wipers 220 - - 223 of the register H<1> are thus brought into circuit with a set of four terminals at the left-hand side of the distributing frame IDF, these terminals being individual to the wanted exchange. After each digit the magnet 153 is energized to step the switch M' to its next position. The fourth, fifth &c. digits are therefore repeated to the magnets 184, 182, &c. to set the thousands, hundreds, &c. registers M<4> - - M<7>. Operation of the register-controller to extend the call to the wanted exchange. This operation commences as soon as the registration of the three exchange digits on the switches M<2> , H' is completed. The relay 203., Fig. 7, which is energized and locks itself at the commencement of the third digit, grounds the wire 231 to energize relay 379, Fig. 8, which short-circuits the relay 375 in the circuit 136, 137 bridged across the first selector trunk. At the termination of the third digit the relapse of relay 202, Fig. 7, grounds the wire 230 to close a self-interrupting circuit for magnet 321, Fig. 9, which steps the switch S<2> to its first position. Ground is now extended through wiper 317 and circuit 340 to the impulse relay 362, Fig. 8, which intermittently energizes magnet 365 to rotate the sending switch S'. At the first step from normal, relay 361 is energized and opens contact 371, so that every subsequent energization of relay 362 produces an interruption of the selector control circuit 136, 137 at contact 374. In the first position of the switch S<2>, Fig.. 9, ground is connected by wiper 319 over circuit 224 to wiper 220 of the switch H', Fig. 7. It will be assumed at first that the exchange called is CARlton (= 422) so that the wipers of the switch H' are on the second set of terminals in the second level. The terminal engaged by the wiper 220 is jumpered at the frame IDF to the bus-bar 3, which is connected to the third terminal in the bank of the wiper 364 of the switch S<1>, Fig. 8. Consequently when, after three impulses have been sent, the wiper 364 arrives at this terminal, relays 360, 376 are energized and lock up in a circuit 382, 394, 385, 390. Relay 376 removes the short circuit from relay 375. Relay 360 open-circuits the impulse relay 362 and closes a self-interrupting circuit to restore the switch S<1> to normal, whereupon relay 361 is de-energized. A circuit 341, by which relay 361 had previously energized magnet 321, Fig. 9, is thus opened, and the relapse of magnet 321 drives the switch S<2> to its second position. It will be seen that the trunks such as 440, 442, Fig. 2, accessible to the selector E' have their battery connections reversed, so that as soon as the selector has found an idle second selector E<2> in its third level the polarized relay 375, Fig. 8, is thrown over and energizes relay 377, which locks itself up and unlocks the relays 360, 376, 378. If, however, the switch S' has not regained its normal position at the moment when relay 377 is energized, relays 360, 376 remain locked up in series with a relay 395. until the return of the switch S<1> to normal de-energizes relay 361. The relapse of relay 360 again completes the circuit of the impulse relay 362, and the transmission of the second digit proceeds in the same way as the first, except that ground is now connected by wiper 319, Fig. 9, over circuit 225 to the wiper 221, Fig. 7, instead of wiper 220, and four impulses are therefore sent, corresponding to the fact that this wiper has been set on a terminal which is jumpered at the frame IDF to the bus-bar 4. At the termination of the second digit the switch S<1> is restored to normal as before, and the de-energization of relay 361 moves the switch S<2> to its third position. As many as four digits can be sent in the same way, further digits being transmitted under control of the wipers 222, 223, but in the present instance it is assumed that the third group of second selectors E<2>, Fig. 2, give access over their fourth level, through non-numerical switches C<1>, Fig. 3, to trunks such as 541, 542 leading direct to the wanted exchange " Carlton," so that only the two digits 34 are necessary. The terminals engaged by the wipers 222, 223 therefore, instead of being jumpered to bus-bars of the numerical series 1 - - 10 are jumpered to the bus-bars 271, 270, which are connected over circuits 238, 239 to the third and fourth terminals of the wiper 318, Fig. 9, so that a self-interrupting circuit is closed for the magnet 321 to move the switch S<2> automatically to its fifth position. It will be assumed next that the wanted exchange is CAPitol (= 421) so that the switch H<1> has been set to the first terminals of its second level. The trunks, such as 585, 586, Fig. 3, to this exchange are wired to the second level of the third selectors E<33>, which are wired to the sixth level of the second selectors E<2>, which are wired to the third level of the first selectors E<1>, so that a series of three digits 362 must be sent. The terminals engaged by the wipers 220, 221, 222 of the switch H<1> are therefore jumpered to the bus-bars 3, 6, 2 respectively, while the terminal engaged by the wiper 223 is jumpered to the blank bus-bar 270. The sending operations are similar to those already described, but the switch S<2> is not moved automatically out of its third position but waits therein until the third digit has been sent. Then it moves to its fourth position, from which it is automatically moved to its fifth position by a circuit 321, 318, 239, 270, 223, 227, 319. As a last instance it will be supposed that the wanted exchange is LIPton (=411) which is reached by way of the Carlton exchange and requires the; four digits 3452. The switch H<1> is set to the first terminals of its first level, these terminals being jumpered to the busbars 3, 4, 5 and 2 respectively. The digits 3, 4 operate selectors E', E<2> to seize a trunk 541, 542, Fig. 3, to the Carlton exchange, and the digits 5, 2 operate selectors E<3>, E<4444>, Fig. 4, to seize a trunk 693, 694 to the Lipton exchange. In all cases the trunk lines between each selector and the next are crossed, so that as soon as a selector is seized the current in the impulse circuit is revers