Patent GB-439067-A (GB)
Title: Switching arrangements in automatic telephone systems
IPC: H04Q3/00
Filed: 1934-09-08
Abstract: 439,067. Automatic exchange systems. TELEFONAKTIEBOLAGET L. M. ERICSSON, 18, D÷belnsgatan, Stockholm. Sept. 8, 1934, Nos. 25902 and 25903. Convention dates, Sept. 8, 1933 and Feb. 12, 1934. [Class 40 (iv)] In a system in which a calling subscriber sets up a connection by sending numerical A.C. impulses, the A.C. source which, as described, is connected up at the exchange in response to a call, is disconnected under the control of an impulse receiver after receipt of a certain number of impulses or impulse trains. In the system described, the A.C. source is disconnected for a first time on local or outgoing calls when the wanted line has tested free or an idle junction is seized, but on outgoing calls is re-connected, to inform the calling party to proceed with dialling, when the incoming apparatus is ready to receive. The impulse receiver may be at the outgoing end of the junction and counts the first outgoing digit. If this indicates a single digit number at the distant exchange, the A.C. source is disconnected, if not, it counts the number of succeeding trains and brings about disconnection of the A.C. source after a predetermined number of further digits, which may be dependent on the first digit. In a simple case for disconnection after say six main exchange digits, a sequence switch may be used as an impulse receiver. The impulse receiver may be connected to the local link and it may bring about the first disconnection of the A.C. source. The impulse receiver may be in the distant exchange and in register-controller systems, the register may act as such and cause a signal to be sent back to disconnect the A.C. source when it has received its full complement of digits. The impulses are repeated over the junction in D.C. form. Local connections. These are set up sub. stantially in the manner described in Speci. fication 433,956. Briefly, the A.C. source VI for dialling tone and impulsing is connected up by relay R8 when switching R6 relay of finder AS1 operates, and is cut off by the release of R8 by test relay R15 when connector LV is set on an idle wanted line. Call to main exchange. The connector is set by a significant digit on an outgoing junction circuit FB1 and test relay R15 disconnects the A.C. source if the circuit is idle. Relay R20 in the junction circuit pulls up and completes a calling loop over R24 which operates when the incoming distant apparatus is ready to receive impulses. R25 pulls up, locks, and operates relay R13 in the local link which energizes R8 to re-connect the A.C. source which signals the calling party to proceed with the dialling. R13 is a relay additional to the relays in the above-mentioned prior Specification, and serves also (1) to operate the ring-tripping relay 17 and (2) at contact 129 to change over the D.C. impulsing circuit, controlled by impulse relay R9, from the connector magnet LVM to the junction circuit where R26 repeats the impulses to selector KV and also over the junction FL, relay R27 operating during the trains to complete a low resistance loop. If the call requires only a single digit (0, 8 or 9) in the main exchange, the selector KV is set by 1, 9 or 10 impulses to a position in which R29 operates to switch through over the junction, and to open the circuit of R13 which releases R8 to disconnect the A.C. source. If a six digit number is to be sent over the junction the first digit (1 to 7) sets KV to a position in which R28 operates, locks, and makes an interrupter circuit for KV which steps to position 9. Relay R27 on operating during each of the five succeeding trains steps KV to position 14 in which R29 switches through and brings about the disconnection of the A.C. source as before. When the calling party sends the clearing signal, R16 operates to release the local link as described in the prior Specification, and R20 in the junction circuit falls back to release that circuit and to initiate release of the main exchange circuits. Connection of A.C. source controlled from main exchange. The junction and incoming circuits, Fig. 2, are substituted for the junction circuit of Fig. 1. The connector LV is set as before and test relay R15 operates in series with R31, Fig. 2, which completes a loop over R33 and the junction to operate R36 at the incoming end, R33 remaining inert. Start relay R37 of finders AS2 pulls up, and when the calling junction is found, R38 operates in series with test relay R39, and a hunting switch RV connects up a register-controller in a manner not shown. The loop relay R33 now pulls up in series with impulse relay R40 in the register-controller, and makes a circuit for R34 in series with R13, Fig. 1, which re-connects the A.C. source to the calling subscriber's line. The calling party now dials the main exchange subscribers' digits which are repeated by R9 to R32, Fig. 2, for repetition over the lower leg of the junction to impulse relay R40, loop relay R33 being held by R32 during the break periods. When the register controller has received the full number of digits, it operates R41 which switches through to a feed relay R45, and removes the shunt on R42 which operates in parallel with R45. R43 pulls up and operates R44 which locks and releases R42 followed by R43 slowly. During its period of operation, R43 holds R45 but releases R33 so that R34 falls back slowly to complete the speaking circuit while R35 opens the circuit to relay R13, Fig. 1, which releases R8 to disconnect the A.C. source. In systems in which register-controllers automatically open the in-pulsing circuit on completion of digit reception, the relay group R42-R44 are dispensed with. The calling subscriber's clearing signal releases the local link as before and R31 falls back to open the junction for the release of the main exchange apparatus.