Patent GB-191328833-A (GB)
Title: Method of Interconnecting Lines by Electro-mechanically Controlled Switches.
Inventor: BARON HAROLD
Filed: 1913-12-13
Granted: 1915-07-15
Abstract: 28,833. Baron, H., [Aldendorff, F.]. Dec. 13. Automatic exchange systems.-Relates to systems of the kind in which the usual two-coordinats group-selecting switches are replaced by simple single co-ordinate switches, the selection of an idle connector serving the desired group of lines being effected by auxiliary switches, which are released as soon as the connexion is effected so as to be available for other calls. Fig. 1 shows the simplified switching-Fcheme of the present invention. Three groups of calling-lines SI, SII, SIII, one hundred lines in each group, are shown connected to the terminals of call-finders FI, FII, FIII in the usual way. The wipers of the call-finders are connected to trunks tI, tII, tIII which terminate in non-numerical switches PTF, termed primary trunk finders, which have access to similar secondary trunk finders STF, which in turn have access to connectors FSr, FSII, FSIII serving the different groups of wanted lines. A call-finder trunk t1, say, can therefore be connected to a group of connectors FSII, say, serving the wanted line, over a trunk t2 and secondary finder STFI, or over a trunk t<1>2 and finder STFII, or over a trunk t<3>2 and finder STFIII. The trunk tI, of a call-finder set in operation to find a calling line, is connected by a non-numerical switch SCI, termed a selectorconnector, with a numerical switch SI, which receives the first set of impulses and serves to bring about the se'ection of an id!e connector FSII in the desired group. This connector is then seized by a secondary finder STFII which is accessible to the primary finders PTF of the calling-group. The primary finder of the trunk tI completes the connexion to the connector. The selector-connector SCI is then disconnected from the trunk tr and connects the group selector SI to some idle call-finder trunk for use in a succeeding call. The number of group selectors SI and selectorconnectors SCI may be small, about two per group of a hundred lines being usually sufficient. In order to avoid confusion in the event of several calls being made simultaneously, the wires from the group selectors SI, SII, SIII to the connectors are preferably net multipled as shown in Fig. 1, but separate selecling-wires are led from each selector to eich group of wanted lines, and special means are provided to enable a secondary finder to identify. the connector designated by a group selector and to enable a primary finder to identify the secondary finder that makes the connexion with the designated connector. These means comprise special identifying-wires connected to each connector, and the auxiliary switches, termed `sieve switches,' shown in Figs. 7 and 8, the function of which will be fully explained later. The working circuits of this modified system are shown in Figs. 2 to 8, of which Figs. 2, 3, 5, 6, 7, 8 should be regarded as assembled side by side, Fig. 4 above Fig. 3, and Fig. 7<a> beneath Fig. 7. The wires at the top of Fig. 8 lead to the wires shown in Fig. 4. The operation of the system in connecting a subscriber SI, Fig. 2, to a connector F<1>1, Fig. 7, of the required group is as follows:- Call-finder, Fig. 2. The removal of a subscribers receiver energizes his line relay 1, which, by closing contact 7, puts a selectable potential upon his test terminal; in the call-finders, and, by casing contact 6, earths the starting-wire SW cf the callfinders. The call-finder to be set in operation is one with which a group selector S'I or S<1>2, Fig. 4, is at that time connected by a selector-connector SC<1>1, or SC<1>2, Fig. 3. If the selector S<1>1, say, is so connected to the top call-finder shown in Fig. 2, current flows from the starting-wire SW, Fig. 2, through the starting-relay r1, contact 12, wiper c5 of the selector-connector SC<1>1, Fig. 3, contact .23, and relay r5 to battery. The relay r1 disconnects itself from the starting-wire, and closes the circuit of the motor magnet M1, which rotates the callfinder until the calling line is reached, when a circuit is closed from earth through the left winding of the subscriber's cut-off relay 2, wiper c3, cut-off relay r2, and wiper c.; of the selector-connector to battery as before. The subscriber's relay 2 disconnects the line relay, and closes a holding-circuit over its right winding, contact 4, and wiper c5. The relay r2 (1) disconnects the motor magnet M1, (2) short-circuits part of its winding so as to make the calling line non-selectable to other call-finders. and (3) connects the calling line over wipers as, b3, contacts 14, 15, and wipers a5, b5 of the selector-connector to the selector line relay R5, Fig. 3. Operation of group selector S<1>1, Figs. 3 and 4. The relay R5, energized over the calling line, short-circuits a relay CR, and opens a short-circuit around the slow-release relay RR, which closes a contact 33 in the circuit of the motor magnet M7. The interruptions of the line circuit, corresponding to the first digit of the wanted number, are repeated by the relay R5 to the motor magnet M7 over contacts 33, 30, 25. At each interruption, the relay RR is momentarily short-circuited-when the armature reaches the limit of its movement, but without effect, and the relay CR is energized owing to the opening of the short-circuit at contact 30, thus isolating the brushes g<1>, g<2>, g<3> during their movement. At the end of the impulses, the relays R5, RR remain energized, and the relay CR connects the wiper g<1> to battery through a resistance 50, and connects the wipers g<2>, g<3> through the wipers d<5>, e<5> of the selector-connector, to the wires q2, q3 of the trunk to the primary trunk finder. Arrangement of primary and secondary trunk finders, Figs. 5 and 6. The call-finder trunks shown in Figs. 2 and 3 terminate in primary finders which are grouped as shown in Fig. 5, three primary finders in each of three groups of calling lines being shown. The terminals of the primary finders are wired to the secondary finders, Fig. 6. in the manner shown in Fig. 1, and the three upper terminals of the secondary finders are wired to connectors of different groups as shown in Fig. 1. Three connectors F<1>1, F<1>2, F<1>3 of one group are shown in Fig. 7. The lowest terminals l<1>, m<1> &c. of the secondary finders are connected by wires j<1>, j<2>, j<3> to special contacts in the secondary sieve switches, one of which is shown in Fig. 7. Arrangements of primary and secondary sieve switches, Figs. 7 and 8. Associated with each group of connectors is one or more pairs of siere switches, each pair comprising a primary sieve switch SW<1>1, Fig. 8, and a secondary sieve switch shown to the right of Fig. 7. Only one pair of sieve switches per group of connectors is shown, the switches. SW<2>1, SW<3>1 shown in Fig. 8 being associated with other groups of connectors. The primary switches SW<1>1 &c. are normally in motion, the wipers w1, w2, w3 moving over sets of terminals connected to the group selectors shown in Figs. 3 and 4, and the wipers w3, w4, w5 moving over terminals connected to the sets of wipers s<1>1, s<1>2, s<1>3, s<1>4, of the secondary sieve switches. As previously stated, separate sets of selecting-wires are led from the terminals of each of the group selectors, Fig. 4, to the terminals of the primary sieve switches, Fig. 8, so that when battery is connected by the brush g' of a group selector, as previovsly described, to the lead p1, say, of one of these sets of selecting-wires, the primary sieve switch SW<1>1 of the desired group of connectors is stopped in a position which is determined firstly by the group of lines in which the call originates, an I secondly by which one of the two (or more) group selectors, associated with this group, is used. The sets of terminals engaged by the wipers w<1>3 w4, w5 are connected in pairs to, the wipers of the secondary sieve switch, Fig. 7, and these wipers move with the wipers w1, w2, w3 so that if the call originates in the first group of calling lines the first set of wipers s'1, s<1>2, s<1>3, s<1>4 becomes operative, whereas if the call originates in the second group, the second set of wipers s<2>1.... s<2>4 becomes operative, and so on. Further, the wiper s<1>1 or s<1>2 becomes operative according as the wipers, w<1>3, w4, w5 rest on the first or second contacts of the pair of sets of contacts, that is according as the. first or second group selector in the calling group of lines is used. If the calling subscriber is in the first group, and uses the first group selector S<1>1, Fig. 4, the first set of wipers s<1>1, s<1>3, s<1>4 becomes operative. The function of the secondary sieve switch is to hunt simultaneously for an idle connector, such as F<1>1, F<1>2, F<1>3, and for an idle secondary trunk finder accessible from the calling group of lines. To this end, the terminals in each row of the secondary sieve switches are divided into sets, engaged respectively by the sets of wipers, and the different sets of terminals in each row are connected by trunks, such as h<1>1, i<1>1, i<1>2, to the contacts of relays, such as R2o, Fig. 6, of different secondary trunk finders, the fourth terminals, such as j<1>, Fig. 7, being connected to terminals such as l<1>, m<1>, Fig. 6, of these secondary trunk finders. Thus, the first set of four terminals of the first row of the secondary sieve switches, that is those terminals engaged by the first set of wipers s<1>1 ... s<1>4, which are operative only when a call originates in the first calling group, are connected to a secondary trunk finder STF<1>1, Fig. 6, accessible from the first calling group ; the second set of four terminals in the same row of the secondary sieve switch, which are operative only when a call originates in the second calling group, are connected to a secondary trunk finder STF'1, Fig. 6, accessible from the second calling group, and so on. Similarly, the first, second, and third sets of terminals in the second row of the secondary sieve