Patent GB-172995-A (GB)
Abstract: 172,995. Automatic Telephone Manufacturing Co., Ltd., Bates, P. T., Mercer, R., and Gillings, C. June 16, 1920. Automatic and semi-automatic exchange systems; metering systems.-Cycles of impulses are continuously produced by an impulse machine common to a number of connecting circuits or to a whole exchange, each cycle being preceded and followed by impulses in separate wires to enable a connecting circuit to intercept a cycle at its commencement and to disconnect itself when the cycle is completed. The impulse machine may be of the kind shown in Fig. 1, with cam-operated springs for producing a fixed number of impulses in a circuit 9, preceded and followed by impulses in circuits 8 and 10; or it may be of the kind shown in Fig. 8, in which different numbers of impulses are produced in circuits 158 - - 161, preceded and followed by impulses in circuits 153 and 169; or it may be of the kind shown in Fig.. 9, in which impulses are produced by a cam 190 and a variable number of them are intercepted between pairs of impulses produced by cams 191 - - 198. The impulses may be employed for operating switches, meters or coinfreed apparatus, several applications to metering systems being shown in the drawings. In these arrangements the meter is connected to the grounded release wire of the connection, and is operated by impulses from a booster battery, such as that shown connected to the springs 6, Fig. 1. Under the action of the cam 3, the circuit 9 is first connected to this battery through a resistance R, is then disconnected from its normal ground, and finally connected to the battery direct. Supplying a fixed number of metering impulses through a repeater E, Fig. 1, at the outgoing end of a trunk line 24, 25. In this arrangement, when the called subscriber answers the call an electropolarized relay 23 is energized by the reversal of the current in its upper winding and connects the starting wire 8 to relay 16. Consequently, at the commencement of the next cycle of impulses, relay 16 becomes energized, locks itself up, connects the stopping wire 10 to relay 33, and connects the impulse wire 9 to the release wire 21. Boosting impulses are now supplied from the springs 6 to operate a marginal meter connected in the circuit 21. At the end of the cycle (in the present case after two impulses have been received), relay 33 is energized over wire 10, locks itself up, disconnects the impulse wire 9, and restores the release wire 21 to its original ground connection at the armature 20 of release relay 17. On the release of the connection, relays 23, 16 are unlocked immediately on the relapse of the release relay 17, but relay 33 is maintained locked and wire 21 grounded for a moment longer by relay 19, which received a momentary current when the line relay 13 became de-energized. Any possibility of a further metering impulse being transmitted over wire 21 is thus obviated. Supplying a fixed number of metering impulses through a connector, Fig. 3. In this arrangement, when the called subscriber answers the call, relay 57 is energized in the ringing circuit, locks itself to ground 66, energizes relay 55, and switches the connection through to energize relay 58, which connects the starting wire 8 to relay 46. At the commencement of the next impulse-cycle relay 46 becomes energized, locks itself up, and connects the release and metering wire 53 to the impulse wire 9. When the cycle of metering impulses has been completed, relay 61 is energized over the stopping wire 10. locks itself up, and unlocks relay 46, so as to disconnect the impulse wire 9. In a modified arrangement, shown in Fig. 2, metering takes place on the release of the connection. On the relapse of the release relay 43, the switching relay 56 is kept energized over the starting circuit 75, which in this case is opened instead of closed by the cam 2, Fig. 1. Consequently at the commencement of the next impulse-cycle, relay 56 relapses and energizes relay 46, which connects the impulse wire 9 through off-normal contacts 79 to the release wire 72. At the end of the cycle, the magnet 83 is energized over the stopping wire 10 and releases the connector. Supplying a variable number of metering impulses according to the number of inter-exchange trunks involved in a connection. Fig. 5 shows metering control switches P, Q associated with repeaters E, G at the outgoing ends of two interexchange trunks through which a connection has been extended. If the connection involves more than two inter-exchange trunks, each additional trunk would be equipped with a similar repeater and metering switch. When the group selector F at the second exchange completes its operation, the energization of its switching relay completes a circuit 126, 127, 128, 120, 129, 130, 131 to energize magnet 132 which moves the switch P at the first exchange a step forward. A moment later this circuit is opened at contact 127. Similarly after the operation of the next group selector, an impulse is transmitted from the third exchange to operate the magnet 137 of the switch Q at the second exchange, and this impulse is repeated at contact 142 to the switch P at the first exchange. The switch P is thus set to a position denoting the number of inter-exchange trunks taken into use, and picks out one of the circuits 158 - - 161 of the impulse machine shown in Fig. 8, to collect a corresponding number of metering impulses. When the called subscriber answers, the reversal of current in each trunk operates an electropolarized relay, such as 147, 118. to reverse the current in the preceding trunk. Relay 118 closes. a circuit through resistance 151 and relay 152, which only energizes sufficiently to close contact 154, connecting itself to the starting wire 153. At the commencement of the next cycle of the impulse machine shown in Fig. 8, wire 153 is grounded and relay 152 becomes fully energized and connects the release and metering wire 163 to the impulse circuit selected by the switch P. At the termination of the cycle the stopping wire 169 is grounded and energizes a magnet 173 which restores the switch P to its normal position. The switch Q at the second exchange operates and is restored like the switch P, but without effect, because the release wire 180 has no meter connected with it except when the repeater G is seized for a call originating at the second exchange. In the modified arrangement shown in Fig. 9, the impulse machine comprises only a single cam 190 for generating booster impulses and a number of pairs of starting and stopping cams 191 - - 198 of which one pair is picked out by the switch P to intercept one, twc, three, or four boosting impulses.