Patent GB-191302302-A (GB)
Title: Improvements in and relating to Selecting Devices for Telephone Systems.
Inventor: KATZ ARON
Filed: 1913-01-28
Granted: 1914-04-30
Abstract: 2302. Katz, A. Jan. 29, 1912, [Convention date]. Automatic and semi - automatic exchange systems.-Means are provided for testing an available outgoing trunk in the required direction, that is to the required group or section of the exchange, from a selector before the latter is taken into engagement. The use of trunk-hunting numerical selectors, such as Strowger group selectors, is thus avoided. As soon as a selector capable of extending the call in the required direction has been found by the so-called path-finder, the latter is released and made available for other calls. The Specification also claims certain arrangements of groups of simple rotary switches, termed primary, secondary, and tertiary elements, which it will be convenient to describe and define before referring to the systems embodying the path-finder principle. Primary, secondary, and tertiary elements. A primary element, Fig. 1, consists of a number, say a, of simple switches, the wipers 14 of which are connected to a incoming leads 1, and the fixed contacts of which are multipled to a outgoing leads 2. Any one of the incoming leads can thus be connected to any one of the outgoing leads. A number of primary elements can be combined to form "incomplete," " semi-cornplete or complete " secondary elements. Incomplete secondary elements comprise two groups 15, 17 of a primary elements as shown in Fig. 5, in which each dot represents a primary element. In both groups, only one of the a primary elements 15x, 17y is fully shown, but each primary element 15 is connected by one lead with each primary element 17, so that any of the incoming leads in the lower row can be connected to any of the outgoing leads in the upper row, provided the trunk between the necessary pair of primary elements 15x, 17y is free. This limitation is largely reduced in the semi-complete secondary element shown in Fig. 8, in which three groups 15, 16, 17 of a primary elements are used, the elements in the middle row being termed " link " elements, while the elements 15, 17 are termed preliminary and final elements respectively. Each link primary element is connected to each final and each preliminary primary element so that a connexion between an incoming lead on a preliminary element and an outgoing lead on a final element can be established over any of the intermediate link elements. It is the duty of the path-finder, previously referred to, to find a link element capable of extending the calling preliminary lead to the required final primary element. In a semi-complete secondary element there are a<2> switches in each row, and a<2> leads between the switches of different rows. The complete secondary element, Fig. 10, is similar to that shown in Fig. 8, but each preliminary element has a switches and 2a bank terminals, so that there are a<2> incoming and outgoing leads and 2a<2> leads to and from the link switches. The complete secondary element is thus able to connect any of the a<2> incoming leads to any of the a<2> outgoing leads. Since the complete secondary element is free from all limitations, the secondary elements can be combined to form tertiary elements in exactly the same way in which secondary elements are made up from primary elements. It is in practice only necessary to use complete secondary elements for the final elements of a tertiary element, incomplete secondary elements being sufficient for the preliminary and link elements. Fig. 12 shows such a tertiary element comprising preliminary, link, and final elements 18, 19, 20, respectively. Construction of selectors. The bank terminals of certain of the switches overlap with so-called spacing-contacts, as shown in Fig. 21. The bank terminals are connected to the multiple cable 37 in the usual way, while the spacing- contacts are multipled to the cable 36. The function of these spacing-contacts is described later in connexion with Fig. 32. The selectors may be ratchet-driven switches of the kind in which the wipers are moved half a step when the armature is attracted and the other half when the armature is released. In the construction shown in Fig. 22, the incoming leads are connected to the rings 11, 12, 13, which can be connected by pairs of brushes on the arm 14 to concentrically arranged sets of contacts such as 21, 22, 23 or 24, 25, 26. Normal and off-normal contacts may be similarly controlled. General operation of system for a small number of subscribers. Figs. 16 and 17 show a system for sixteen lines, Fig. 16 being a semi-complete secondary element whose basic number is four, that is to say it comprises preliminary, link, and final sections, each preliminary section consisting of four primary elements 181, 182, 183, 184, each having four incoming wires such as 141, 142, 143, 144 and four outgoing wires such as 421, 422, 423, 424, each link section consisting of four similar primary elements 191, 192, 193, 194, and each final section consisting of four similar elements 201, 202, 203, 204. The subscribers' lines are connected as calling lines to the preliminary elements and as called lines to the final elements. Each preliminary element is connected to each link element, and each link element to each final element. A calling line can thus be connected to a particular subscriber in four ways, that is over any of the four link elements, provided that the necessary pair of leads incoming to and outgoing from the link elements are free. In order to select a suitable link element, the apparatus shown in Fig. 17, termed a path-finder, is used temporarily, and is then released for use by other subscribers. The path-finder consists of two sets of four primary elements, the switch arms of the upper set being connected to the calling lines, the contact banks to the switch arms of the lower set, and the banks of these to the switch arms of the final elements in Fig. 16. If a subscriber T wishes to call subscriber 43, he first moves his switch 144d, Fig. 17, four steps, thus seizing a trunk 424d terminating in a switch 147d, the outgoing trunks from which lead to a final element 204 serving the lines 41 ... 44. The switch 147d is coupled by means of circuit connexions described later to the calling subscriber's non-numerical switch 144, Fig. 16, and both switches rotate synchronously until each finds an idle trunk, that is until they find a link element 193, say, having an idle incoming trunk 423 from the switch 144 and an idle trunk 534 outgoing in the required direction to the switch 149 capable of extending the connexion to subscriber 43. The pathfinder is then disconnected, and the calling subscriber again transmits four impulses to move the link switch 193 four steps to connect the calling line to the switch 149, which is then moved three steps to select the wanted line. Detailed operation of a system for a larger number of subscribers. Figs. 27 to 34, which must be combined as shown in Fig. 26, show the circuit arrangements of a tertiary element in a 10,000-line system. In these Figures, the numerals I to VII represent primary elements forming the speaking connexions; I and II are preliminary and final elements of a secondary preliminary element, III and IV are the preliminary and final elements of a secondary link element, and V, VI, VII are the preliminary, link, and'final elements of a secondary final element. The numerals I<1>-IV<1> represent the elements of a path-finder which selects a suitable secondary link element III, IV, and the elements V<1>, VI<1> are the path-finder elements which are used to find a suitable link element VI of the secondary final element V, VI, VII. In each Figure, the wedge-shaped bodies represent switch arms, the incoming line being connected to the thin end of the wedge, and the outgoing lines to the thick end. The lateral connexions such as 3a, 3b, Fig. 28, to some of the wedges represent leads to normal contacts of the switches. In the case of the switches F, G the second lead from the thick end of the wedge indicates the multiple cable connected to the spacing-contacts as described in connexion with Fig. 21. All the switches of the same Figure shown vertically above one another are mechanically combined and simultaneously moved by the motor magnets 34. In this abridgment, the same letters or numerals are used to denote similar switches, relays, contacts, &c. in all the Fgures, but the Roman numerals associated with each reference character serve to distinguish these similar parts. The system described is of the reverting-impulse type, the subscriber's dial sender being set by hand and returned step by step to normal by a magnet. When the dial is set, a circuit is closed through its operating-magnet (not shown in Fig. 27) and the motor magnet of an exchange selector, which in rotating repeatedly interrupts the line circuit until the dial reaches normal and permanently opens the circuit, thus arresting the selector. Operation of path-finder switches, Figs. 32 and 33, and selection of idle link element. When the subscriber T, Fig. 27, removes his receiver and operates his dial-sender S, current passes over the leads 1b, 10, Figs. 28 and 32, contacts 73, 33, n, operating-magnet 34 (I<1>), slow-release relay 35 (I<1>), and normal contact of switch G to battery 43. After the first step, the switch contact n, Fig. 32, is opened and contact 33 closed so that the circuit is maintained over contact 33. As the arm of switch G passes from one bank terminal to the next, it interrupts the line circuit, and closes a local circuit over the spacing-contacts (see Fig. 21), battery 38 and relay 35, so that the latter is not deenergized until the line circuit is permanently opened at the sub-station. All the preliminary switches R I<1>, G I<1>, D I<1>, Z I<1>, Za I<1>, P I<1>, &c. have thus been connected to trunks leading to the required final element of the incomplete secondary element shown in Fig. 32. If the selected trunk is in use, its rel