Patent GB-185723-A (GB)
Abstract: 185,723. Automatic Telephone Manufacturing Co., Ltd., (Assignees of Owen, W. W.). Sept. 7, 1921, [Convention date]. Automatic exchange systems; metering systems.-In a system in which long-distance calls may be set up over a number of exchanges and in which a calling-subscriber's meter is operated at regular intervals throughout the conversation by varying amounts dependent, upon the connection obtained, a number of interrupters capable of generating different numbers of impulses per unit time are associated with each exchange, and an auxiliary switch individual to the outgoing selector at the originating exchange is operated in accordance with the route over which the call is set up to determine which of the interrupters shall be employed. In one arrangement, a single set of continuously-operating interrupters is common to the exchange and may be employed simultaneously for a number of calls, another continuously-operating interrupter so controlling the circuits that the speaking circuit is not closed, and a tone signal is transmitted to the called subscriber to notify him of that fact, until the interrupters are in a correct position for commencing the metering operations. In a second arrangement, a number of sets of interrupters are employed, and a hunting switch preselects an idle set, the connection being completed and the metering operations commenced: as soon as the called subscriber replies. In the system described, a call is extended over a line switch and first group selector of standard type to a selector repeater E, Fig. 2, at the first exchange, which selects an idle trunk 45, 39 leading to a selector F at a second exchange, Fig. 3. The selector F responds to impulses repeated by the switch E to select an idle selector repeater G which extends the call over a trunk 74, 75 to a third exchange, Fig. 4, at which a group selector I and a connector of standard type complete the connection. Selectors F, I, when taken into use, send back booster impulses corresponding to the charges made for the useof the trunks 45, 39 and 74, 75 respectively, and the auxiliary switch B responds to these impulses to select the appropriate interrupter. Metering trunk calls. First arrangement, Figs. 2-4. At the end of the vertical movement of the selector repeater E in response to the second set of impulses, the slow release relay 18 completes a circuit for the rotary magnet and the wipers 19, 20, 21 are rotated step by step in known manner under the combined control of the rotary magnet 23 and stepping relay. 22 until an idle trunk 45, 39 is reached, whereupon relay 24 energizes in series with relay 22, locks up, and opens the circuits of the vertical and rotary magnets. Relay 24 also completes a. bridge circuit across the selector including relay 42 and the upper winding of polarized relay 43 in series with which the line relay 36 of the selector F energizes. Relay 42 closes a circuit for the lower winding of relay 43 which does not yet energize since the currents through its windings are in opposition. The metering equipment at the selector E comprises interrupters M, N, O, P, mounted on a common shaft which rotates, say, once per minute, the wipers 58 - - 61 passing over different numbers of grounded contacts so as to control the transmission of corresponding numbers of impulses. As soon as the line relay 36 of the switch F energizes, a, relay 53 transmits a booster impulse from a battery Y over the conductor 39 to the driving magnet 48 which steps forward the switch B on to its first set of contacts. The next set of impulses transmitted by the calling subscriber is repeated over the trunk 45, 39 by the line relay 15 at its contact 41 to operate the selector F, the bridged windings of relays 42, 43 being short-circuited by relay 18 during the transmission of the impulses. Selector F in known manner selects an idle selector repeater G which is similar to the switch E and extends the connection to a selector I at the third exchange. Line relay 83 energizes in series with relay 100 and the upper winding of polarized relay 99, and two booster impulses from battery Y<z> are transmitted by relays 81, 300 over the conductor 75 and repeated by magnet 78 over the conductor 39 to the magnet 48 which steps the switch B to its third set of contacts corresponding to the third interrupter O. The next set of impulses is repeated by switches E, G to the selector I which selects an idle connector, over which the connection is completed in known manner. When the called subscriber replies, the reversal of current over the talking- circuit produced by the back-bridge relay at the connector, energizes polarized relay 99 which completes a circuit for reversing relay 102. The consequent reversal of current over the trunk 45, 39 energizes polarized relay 43 which prepares a circuit for relay 49. An auxiliary wiper 106 on the interrupter shaft passes over a grounded contact once per revolution an instant before the interrupter wipers 58 - - 61 are in position to commences the transmission of impulses. If the interrupters are not in this position when the called subscriber replies, a special tone signal is transmitted to him from the machine K, but as soon as the wiper 106 arrives at its grounded contact, relay 49 energizes over the arm 109 of the switch B to disconnect the tone signal and complete the talking circuit. Relay 49 also completes the metering circuit which extends over contacts 60, 104, 103, 64 to the calling- subscriber's meter over fourth wipers and contacts of the switching relays of the first group selector and the line switch, three impulses per minute being transmitted over this circuit as long as the conversation continues. When either subscriber hangs up, the de-energization of relay 16 or 43 disconnects the metering circuit. The operating magnet 48 is disconnected from the lower talking conductor during impulse-transmission by the relay 18 and during conversation by the relay 43. Second arrangement, Figs. 5 and 6. The selector repeater V, Fig. 5, corresponding to the switch E, Fig. 2, is provided with a hunting switch S which preselects an idle set of interrupters from a number of such sets 352, 357, 355, 356, the auxiliary switch B<2> then operating in the same manner as the switch B, Fig. 2, in accordance with the connection obtained to select the appropriate interrupter from the preselected set. Assuming that the switch B<2> has been stepped on to the third set of contacts as before and that the switch S is resting on the first interrupter set 352, the polarized relay 243 energizing in response to the reply of the called subscriber closes a circuit 244, 245 for the self-interrupting driving magnet 301 of the interrupter 352 and for the relay 305, metering impulses being transmitted as before over the circuit 350, 351, 347, 324, 248. Metering ceases as soon as either subscriber hangs up, but if the interrupter is at this moment in an off-normal position, a circuit is completed over wiper 352 for continuing its rotation to normal. The wipers 352 - - 357 are constructed so that no break occurs in moving from one contact t) the next so that an earth connection is maintained to effect the complete operation of the associated magnets. If the interrupter set on which a switch S is standing becomes busy, the driving magnet 309 energizes over contacts 239, 353, 352 and steps the switch forward until an idle set is reached. In both arrangements, the holding pawls 105 of the switches B, B<2>, are released by the release magnets of the associated switches. Metering local calls. The circuit of the meter of a calling subscriber engaged in a local call extends over fourth wipers and contacts of the switching relays of the line switch and group selector and is completed over a fourth terminal of the connector by the ringing-cut-off relay when the called subscriber replies so as to operate the meter once per call. Each line may also have a reverse-battery meter controlled by a pclarized relay in series in the line circuit to register all local calls, in which case the fourth terminal of the connector may be dispensed with, and the other meter records only long-distance calls.