Patent GB-191409840-A (GB)
Title: Improvements in or relating to Automatic or Semi-automatic Telephone Exchange Systems.
Inventor: BETULANDER GOTTHILF ANSGARIUS
Filed: 1914-04-21
Granted: 1914-11-19
Abstract: 9840. Betulander, G. A. April 23, 1913, [Convention date]. Automatic exchange systems. - A group of 100 subscribers is divided into sub-groups I, II ... X, Fig. 3, each of which has a set of intermediate lines 4 through which the subscribers' lines are connected with the incoming and outgoing junction lines 6, 7, which are common to the whole group. Each intermediate line 4 can be connected to one outgoing junction line 7 and also to one secondary intermediate line 10, which can be connected to any of the incoming junction lines 6. In the case of an outgoing call, means are provided for connecting the calling-subscriber's line to an intermediate line 4, which is both idle itself, and of which the corresponding outgoing junction line 7 is also idle. In the case of an incoming call, means are provided for connecting the incoming junction line 6 to a secondary intermediate line 10, which is both idle itself, and of which the corresponding intermediate line 4 in the wanted sub-group of subscribers is also idle. The arrangement represented in Fig. 3 is a complete unit for a group of 100 subscribers. If the exchange consisted of only one such group, each outgoing line 7 would be permanently connected to one of the incoming lines 6, but in a larger exchange group-selecting devices would be provided for connecting an outgoing line 7 to an idle incoming line 6 in the wanted group. The invention can be carried out by the use of electro-mechanical switches, in which case, it effects a saving in the number of switch-contacts required; but it is of special utility in systems of the kind described hereafter, in which the connexions are made entirely by relays. In this case, each of the contacts 3, 8, 9, 11 represents a separate connecting- relay. Since the number of immediate lines 4 in each sub-group is less than the sum of the incoming and outgoing junction lines 6, 7, the invention effects a saving in the total number of relays required, for each subscriber's line needs to have associated with it only as many relays as there are intermediate lines, the same relays 3 serving for both incoming and outgoing connexions. The other relays, corresponding to the contacts 11, 9, 8, are common to all the subscribers in a group or sub-group, and are therefore comparatively few. A still greater economy of relays can be effected by reducing the number of intermediate lines and enabling each of them to obtain access to two outgoing junctions 7 and two secondary lines 10. This modification is shown in Fig. 4, in which there are 20 sub-groups of 5 subscribers, each having 5 intermediate lines 4. Moreover, the number of relays 11 can be reduced by providing tertiary intermediate lines between the incoming junction line 6 and the secondary lines 10. The system represented skeletonically in Fig. 3 is shown in detail in Figs. 7, S, 9, and 10, which should be assembled side by side. In these Figures, it should be noted that only three lines and relays out of each set of ten are represented. Connexion of a calling subscriber A, Fig. 9, to an idle outgoing junction line 45, 46, Fig. 10. From an inspection of Figs. 9 and 10, it will be seen that a calling- subscriber's line can be connected by means of relays 43 to any of the intermediate lines 33, 34, and that each of these can be connected by relays 47 to one of the outgoing junction lines 45, 46. The lower windings of the connecting-relays 43, 47 are connected between vertical and horizontal sets of wires 59, 57 and 61, 60, respectively, and the energization of the appropriate relays is effected by connecting battery between selected vertical and horizontal wires of each set. The task of finding an idle intermediate line giving access to an idle outgoing junction line, and of energizing the appropriate relays for connecting the calling-subscriber to these lines, is performed by a device called a "searcher," which is shown at the top of Fig. 10. This device operates almost instantaneously and is then set free, so that only one of them need be provided in each group of 100 lines. When a calling-subscriber lifts down his receiver, the two branches of his line circuit are grounded, and his line relay 41 becomes energized and energizes relays 50, 51, Fig. 10. The relay 51 energizes a relay 52 and connects the test wires 69 of the intermediate lines of the subgroup to which the calling-subscriber belongs with the test wires 71 of the junction lines to which they give access. The test relay 48 of a junction line is consequently energized either if the junction line itself is engaged, or if the corresponding intermediate line of the group accessible to the subscriber A is engaged. The first relay 48 which is at this moment in an unenergized condition corresponds therefore to the first outgoing junction line available to the subscriber A, and it will be seen that the corresponding relay 49 will be energized when the relay 52 responds to the current sent through it by the relay 51. The relay 49 locks itself up and connects battery to the horizontal wire 60 corresponding to the selected junction line, and also (since corresponding wires of the sets 57 and 60 have been connected together by the relay 50) to the horizontal wire 57 of the corresponding intermediate line. A ground connexion has already been made by the line relay 41 to a vertical wire of the set 59, Fig. 9, and also to a vertical wire of the set 61, Fig. 10, and the relays 43, 47 necessary for connecting the calling line to the selected intermediate line and outgoing junction are therefore energized. These relays lock themselves up in a series circuit 66, 64, 65 through their upper windings, and remain locked until the calling subscriber hangs up the receiver, the junction line locking- wire 66 being grounded by a relay (not shown) which is energized over the subscriber's line circuit. The locking-circuit includes the subscriber's cut-off relay 42, the energization of which de-energizes the line relay 41 and the searcher relays 50, 51, 52, &c., so that the searcher is at once set free for further service. The connexion is now extended by means which are not described to one of the incoming junction lines 15, 16, Fig. 7, of the group of 100 subscribers to which the wanted subscriber belongs. In the example shown, the wanted subscriber B, Fig. 9, is assumed to belong to the same group of 100 lines and also to the same sub-group of 10 lines as the calling- subscriber A. Connexion of an incoming junction line 15, 16, Fig. 7, to the wanted subscriber B, Fig. 9. From an inspection of Figs. 7 and 8, it will be seen that each incoming junction line can be connected by relays 17 to any of the secondary intermediate lines 18, 19, Fig. 7, (10, Fig. 3), and that each secondary intermediate line can be connected by relays 32, Fig. 8, to one intermediate line 33, 34, Fig. 8, (4, Fig. 3), in each sub-group of 10 subscribers. The lines 33, 34 which pass from Fig. 8 into Fig. 9 are those which belong to the sub-group of subscribers including the wanted subscriber B. The lines 33, 34 can, as already explained, be connected with the subscribers' lines by relays 43, Fig. 9. The relays 17, 32, 43 are selected, as explained above, by energizing the particular vertical and horizontal wires between which their lower windings are connected. The task of finding and testing the line of the wanted subscriber is performed by a " line selector " shown at the foot of Fig. 7, to which the incoming junction lines can be connected by relays 20, and the task of finding an idle secondary line 18, 19, giving access to an idle intermediate line 33, 34 of the sub-group of 10 lines to which the wanted subscriber B belongs, is performed by a searcher shown at the top of Fig. 8. The line selector and searcher are released for further service as soon as the necessary connecting - relays 17, 32, 43 have been energized to complete the speaking-connexion. Operation of the line selector, Fig. 7. The tens and units sets of impulses are delivered to the line selector shown at the foot of Fig. 7, to which the incoming junction line 15, 16 has been connected by a relay 20. The tens impulses build up a chain of relays 23 and determine the application of a selecting-potential to one of a series of " marking-wires " 111, while the units impulses build up a chain of relays 24 and determine the application of potential to one of the marking-wires 123. The selected tens wire III energizes one of the relays 35, Fig. 8, to determine in which sub-group of 10 subscribers an idle intermediate line 33, 34 shall be found by the searcher, and energizes a relay 44, Fig. 9, to connect the units wires 123 to the subscribers' wires 125 in that subgroup. The selected units wire 123 determines which subscriber shall be selected in the subgroup determined by the tens wire. When the line selector is seized, the relays 26, 27 are energized over the line 16, and the lowest of a chain of auxiliary relays 25 is energized over the line 15. The relay 25 energizes the first tens and units relays 23, 24, which lock themselves up. The line circuit 15 is then interrupted a number of times corresponding to the tens digit of the wanted number, while the circuit 16 is kept closed. The first interruption de-energizes the bottom relay 25, and when the circuit 15 is closed again, the second relay 25 is energized and locks up the second tens and units relays 23, 24. In the same way. succeeding impulses cause the energization of succeeding relays in each of the chains 23, 24, 25. At the conclusion of the tens impulses, w h e n the chain of tens relays 23 has been built up to the point at which a circuit is prepared for the desired tens wire 111, the line circuit 16 is momentarily interrupted to de-energize the relay 26, which unlocks all the energized units relays 24, the energization of these relays by the tens impulses being merely incidental and without effe