Patent GB-191201658-A (GB)
Title: Improvements in Registering Calls between Telephone Exchanges Provided with Automatic Selectors.
Filed: 1912-01-20
Granted: 1912-08-01
Abstract: 1658. Siemens Bros. & Co., [Siemens & Halske Akt.-Ges.]. Jan. 20. Automatic exchange systems ; metering systems.- Relates to a differential metering-system in which a higher rate of charge is registered for calls of a special kind, such as junction or trunk calls. Special devices which bring about the operation of the register of the calling subscriber are connected to the leads over which, or to the apparatus by which, the connexions are established, so that the register is actuated when the called subscriber replies. In the system described, the register circuit is closed a number of times depending upon the rate to be charged, but instead of repeatedly closing the circuit, different kinds of current may be used to actuate the register selectively. The invention is described as applied to a two-wire system in which the selectors and connectors are controlled by quick-release and slow-release relays, no side switches being used. The system is identical, except as regards the metering-arrangements, with that described in Specification 19,185/11. The special device for differential metering is shown at E, Fig. 1, as connected in the out-going end of a junction line, and comprises a differential relay Di controlling a relay m which connects the self-interrupting magnet r of a stepby-step switch s over a contact q to the a-lead. The windings of the relay Di are in the a and b leads, so that the relay is not affected by the selecting-impulses which pass over these leads in series to the connector. In a modified form of device, the same connexions can be registered differently for different subscribers, for instance for those whopay a flat rate for ordinary calls, and those who pay for each call separately. General operation. The operation of the preliminary selector, group selector GW, and connector LW takes place in exactly the same manner as in Specification 19,185/11, and it will be sufficient for the purposes of this abridgment to refer only to the points affecting the metering-arrangements. When an idle group selector is found, the register Z, in parallel with the low-resistance winding of the cut-off relay TR, is connected in the testcircuit in series with the resistances 4, 5, which prevent the operation of the register at this stage. The resistance 5 can be repeatedly short-circuited by a relay ZR, which is connected to the a-lead until the whole of the selecting - impulses have been transmitted, and the connector wipers have been brought on to the contacts of the called subscriber. When this has been done, the relay V, Fig. 2, de-energizes, and connects the battery over a contact K<6>, coil D<r>, and armature 40 to the lead b<2>, thereby energizing the differential relay D<i>, and a relay J', the circuit of which has been prepared by the relay J. The relay J<1> locks-up over its armature 21, disconnects the relay J, and connects the relays ZR, ZR' to the a-lead. The relay D<r> opens a shortcircuit round the relay m, which now energizes in series with the relays P, Fig. 1, and C', Fig. 2. The relay m removes a short-circuit round a reresistance w in the a-lead, and connects the selfinterrupting magnet r of the step-by-step switch s to the a-lead over a contact q. As the a-lead is not earthed, neither the relays ZR, ZR' nor the magnet rare affected. When, however, the called subscriber replies, the relay Y earths the lead a' over the armature 39, so that the magnet r rotates the switch s. When the circuit of the low-resistance magnet r is closed, the potential at the point x is such that the relay ZR is not energized, but at each interruption of the circuit of the magnet r, the relay ZR is energized and causes the operation of the meter Z by short-circuiting the resistance 5. After a predetermined number of steps, the wiper of the switch s short-circuits the resistance w, thus increasing the current in the a-lead sufficiently to energize the relay ZR and also the less-sensitive relay ZR', which opens the holding-circuit of the relay J<1>, and thereby disconnects the relays ZR, ZR' from the a-lead. If a connexion is made with a junction line not provided with the device E, the relays ZR, ZR<1> are energized together, and the registering circuit is interrupted after the first registration. Fig. 3 shows the modification of the device E whereby different subscribers can be charged at different rates. The different subscribers must be divided into groups in such a manner that they connect up to the same junction lines over different group selectors, which have access to the group of terminals x, y, z or x<1>, y', z<1>. In the case of selectors connecting up to the terminals x, y, z, registration takes place as previously described, the resistance w being then in circuit with the a-lead. If, however, the junction line is engaged over the terminals x<1>, y<1>, z<1>, a resistance w<1> is short-circuited by a second arm s' moved with the arm s, and this short-circuit may occur after a different number of steps.