Patent GB-242594-A (GB)
IPC: H04Q3/42
Filed: 1925-07-31
Abstract: 242,594. Barnay, A. Nov. 8, 1924, [Convention date]. Automatic exchange systems. -In a system employing register-senders and single-motion selectors controlled by marking switches set by impulses received from the register-sender, means are provided for preventing the retransmission of a digit by the register-sender until an idle switch which is to receive it has been engaged. This control is effected by a relay group C, Fig. 1, or C<1>, Fig. 2, associated with the register-sender E, Fig. 1, or E<1>, Fig. 2, which after it has retransmitted a digit energizes a relay 53. As long as the relay 53 is energized the impulse circuit is disconnected and the operation of the sender held up, but when a switch intended to receive the next digit is engaged, earth sent back over one of the line wires causes the relapse of this relay, and the register-sender is again started and the impulse circuit connected up. Assuming that the register-sender E, Fig. 1, has transmitted a digit to the group selector S<1> which has seized an idle second group selector S<2>. The relay 19 energizes over its upper winding and the earthed test wire 23, locks over its lower winding, and connects up the marking switch, the line relay 11 of which energizes the slow-release relay 29. The sender E now transmits impulses over the line wires 17, 14, thereby causing the intermittent energization of the stepping magnet 34 of the marker which marks a group of lines in the bank of the control wiper 49. When the marker leaves its normal position, the group selector stepping magnet 40 is energized and steps the main switch until the first line of the wanted group is engaged, when the relay 47 responds and arrests the switch. At the end of the impulse series, the slow relay 36 falls away and closes a hunting circuit 42, 43, 66, 67, 45, 46 for the magnet 40. The register-sender E also in known manner temporarily earths the relay 53, which energizes over parallel contacts 54, 55, locks over armature 55<1>, disconnects the sender E and in any suitable manner arrests its operation, and earths the, upper line wire 17 to hold the line relay 11. The circuit of the slowrelease relay 59 is opened by relay 53, and the relay 57 is energized over the line wire 14 until the relay 36 has relapsed, but when both relays 59, 57 have fallen away, relay 62 is energized, locks over armature 60, and opens at armature 55 one of the exciting paths of the relay 53. If all the lines in the wanted group at the selector S<2> are busy, the wipers pass on to the first line of the next group and the relay 47 relapses, but a further stepping circuit 44, 45, 46 is closed for the magnet 40 until the wanted group is again engaged, when the relay 47 again energizes and the first-mentioned hunting circuit is remade. When a line in the wanted group falls idle and is engaged by the selector, the test relay 69 is energized, locks up, opens the stepping circuit, deenergizes relay 19 to disconnect the marking switch, and'connects the line wires 17, 14 to the next selector. The lower line wire 14 is now earthed at the off-normal springs (such as 12, of selector S<2>) of the marking switch at the next selector, and the relay 57 of the relay group C energizes and at armature 54 opens the remaining circuit of relay 53, which after an interval sufficient to ensure certainty of operation, relapses, connects up the sender E and causes it to transmit the next digit. In the modification shown in Fig. 2, the system is of the kind described in Specification 235,578, in which the impulses from the register-sender E<1> only pass over one line wire 5, 14, whilst the selectors S<1>1, S<1>2 are of the kind which do not commence hunting until their marking switches have been set. When the connection has been extended by the first selector S<1>1 to an idle second selector S'2, relay 19 is energized over its upper winding, locks up over both its windings in series, earths the upper line wire 17, connects up the marking switch, and energizes a relay 94 which disconnects earth from the common wire 95 to guard all the other selectors served by the marking switch. Each impulse in the next series now sent from the register-sender E<1> energizes the line relay 92, which closes the circuit of the stepping magnet 34 to position the marking switch. On the cessation of these impulses, the relay 53 in the relay group C' is momentarily energized in any suitable manner from the register-sender E<1>, locks up, energizes a slow-to-act relay 99, closes a series circuit for relays 57 and 92, and disconnects the register-sender E'. Relay 57 being of high resistance responds, but relay 92 remains inert : relay 57 opens the circuit of relay 9 before it has time to pull up. In the selector S'2, the relapse of the slow-release relay 36 closes a stepping circuit for the magnet 40 which is opened by the response of relay 47 when the first line of the wanted group is engaged. A relay 102 is also locked energized at this time, and disconnects earth from the wire 14 and the relay 57, which relapses and energizes relay 99. Relay 99 locks up. The selector is now rotated until it finds an idle line in the wanted group, or until a line in this group falls idle, at which time the test relay 69 energizes and brings about the same operations as in the first system. The connection of earth to the lower line wire 14 through the line relay, such as 92, at the next switch, re-energizes relay 57, which short-circuits relay 53. The relapse of relay 53 connects up the sender E<1> and causes it to transmit the next digit. The invention may be used in systems employing selectors with two or more sets of wipers, as described in Specifications 223,985 and 233,339.