Patent GB-155833-A (GB)
IPC: H04M7/06
Abstract: 155,833. Automatic Telephone Manufacturing Co., Ltd., (Assignees of Homrighous, J. H.). Dec. 27, 1919, [Convention date]. Automatic and semi-automatic exchange systems.-A series of impulses is transmitted in succession from one to another of a number of serially related exchanges until the exchange corresponding to the number of impulses sent is reached. The invention is described as applied to a semi-automatic system in which a trunk operator inserts the calling plug of her cord into one of a number of jacks J<1> - - J<6>, Fig. 1, according to which one of a number of exchanges 1-6 she desires to extend connection. Assuming it is desired to extend connection to No. 5 exchange, she will plug into the jack J<5> of an idle outgoing trunk line, whereupon a rotary switch S operates to send five impulses over the line to raise the wipers of the trunk selector of No. 1 exchange five steps, after which an idle outgoing line to No. 2 exchange is selected in the usual manner. A rotary switch associated with the trunk selector of No. 1 exchange will now send five impulses to raise the wipers of the trunk selector of No. 2 exchange to the fifth level, after which the selector will select an idle outgoing line to No. 3 exchange. The operation will continue in a similar manner until connection is extended to a trunk selector in No. 5 exchange, which is raised to the fifth level, wherein the local trunk lines LT terminate. The call mav now 'be completed by the operator in the usual manner. The number of serially related switches employed for a certain connection may vary according to the route over which connection is established. In the arrangement shown, the outgoing trurk lines at No. 1 exchange are divided into two groups which extend to No. 2 and No. 3 exchanges respectively, connection being extended to exchange No. 4, say, through either No. 2 or No. 3 exchange. A call to No. 2 exchange may be routed through No. 3 exchange, the trunks on the second level of which are extended direct to No. 2 exchange. Control of runk selector of No. 1 exchange by insertion of plug. Assuming it is desired to extend a connection to a subscriber in the No. 2 exchange, the operator inserts the plug P in the jack J<2>, Fig. 2, and depresses the calling key K<1> and the listening key K<2>. The line relay 43 of the trunk selector E, Fig. 3, of No. 1 exchange is thereby energized in series with relay 4 over the conductor 31. Actuation of relay 4 (1) lights supervisory lamp L<1>, (2) puts earth potential on the second contact of rotary switch S, and (3) energizes the starting relay 12. The stepping magnet 14 is thereby energized and the wiper 29 is rotated until the earthed contact is engaged. At each energization of the magnet 14 the relay 11 is actuated, and the circuit through the linerelay 43 is interrupted by the armature 10. The wipers of the trunk selector E are thereby raised to the second level and then select an idle trunk to No, 2 exchange in the usual manner. The auxiliary wipers 84, 85 are also raised to their second level by the vertical movement of the switch, but remain stationary during the rotary movement. Consequential control of trunk selector of No. 2 exchange. Response of switching relay 44 extends earth to the second contact of switch S<1> over wiper 85, and energizes relay 105. Line relay of trunk selector of No. 2 exchange is thereby energized in series with relay 101 over the armature 117, relay 40 is actuated to connect line conductors 30, 32 direct to wipers 80, 83, and the stepping magnet 103 operates to rotate wiper 107 until the earthed contact is reached. At each energization of magnet 103, the relay 102 interrupts at armature 112, the circuit of the line relay of the trunk selector at No. 2 exchange, thereby raising its wipers to the second level, where they are rotated to find an idle local trunk. Operation of the line relay at No. 2 exchange causes the right-hand winding of the repeating coil, similar to R, to form a loop across the trunk conductors, thus making the connector ready for the reception of impulses. Operation of local connector by operation of operator's impulse-sender C. At each interruption the line relay 43 de-energizes and completes a circuit through relav 102 which at armature 112 produces a corresponding impulse in the circuit of the line relay at No. 2 exchange. This operates as a repeater to produce an interruption in the loop across the trunk conductors extending to the connector, which acts in the usual manner to extend connection to the desired subscriber. Supervisory signals. Having finished dialling, the operator restores calling key K<1>, thereby lighting lamp L<2>. When the wanted subscriber replies, current through one winding of a polarized relay (similar to 41), in the trunk selector of No. 2 exchange, is reversed, its armature is attracted and inserts a high resistance in series with the line relay of the switch. The low-resistance relay 101 thereby relapses, relay 42 is energized, and connects a resistance 66 in series with the line relay 43 of the trunk selector E. The lowresistance relay 2 then de-energizes and the lamp L<2> is extinguished. When the wanted subscriber hangs up, current through the polarized relay is again reversed and the lamp L<2> operated. Release. This is effected by removal of plug P at the operator's position. The line relay 43 de-energizes and the selector E and subsequent switches are restored in the usual manner. Relapse of the switching relay 44 causes the deenergization of relay 105 and the restoration of switch S<1> by the release magnet 106. Restoration of switch S at the operator's position is effected by the relapse of relay 4. Specification 120,483 is referred to.