Patent GB-265971-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/00
Filed: 1927-02-08
Abstract: 265,971. Associated Telephone & Telegraph Co., (Assignees of Stehlik, R. F.). Feb. 12, 1926, [Convention date]. Automatic exchange systems; metering.-The invention relates to that type of zone and time metering arrangement in which a discriminating switch, associated with the outgoing trunk, is actuated by some or all of the exchange digits to control the number of units metered in accordance with the zone in which the call is made, and consists in temporarily associating such switch with the outgoing trunk and dissociating the switch therefrom just after it has been set. The repeater of each outgoing trunk, which is seized over a first selector E<1>, Fig. 1, is permanently connected to a zone metering relay group ZMR. Fig. 2, and a time metering switch TMS, Fig. 3. A set of discriminating up-and-around switches ZM, Fig. 2, are associated with the repeater-groups by hunting-switches F under the control of a common distributor switch D. The outgoing trunks are selectable only when associated with a switch ZM. The bank terminals of the switches ZM are so connected that one, or other, or both relays 206, 207 in group ZMR are energized to connect up the contacts of one of three initial charge cams IC1 - - IC3, and one of three wipers TC1 - - TC3 of the switch TMS so as to apply boosterbattery to meter M, Fig. 1, for the initial charge, and for each succeeding time interval in accordance with the zone in which the call is made. When the connection is effected, the switch TMS immediately selects that one of a series of sets of time cams C1 - - C3 differing in phase, which is just starting a new cycle. The initial-charge, and time cams are common to the exchange. Setting up connection. When subscriber A removes his receiver, the usual no-normal line switch finds an idle selector E<1> which in response to the first set of impulses seizes a repeater R. Relays 22, 23, 25 operate, feeding back holding earth through contacts 235, 35, and at 41 energizing the polarizing winding of relay 24. Relay 22 repeats the impulses for the remaining four digits at contact 32 to operate the remaining selectors and the connector. When the called subscriber answers, reversal of current in leads 50, 51 and 9, 11 takes place. Operation of zone marking switch ZM during dialling. For the repeater R to be selectable, a switch ZM must be associated with the repeater and its zone metering group ZMR, so that relays 201, 211 operate, removing earth at contact 230 from test lead 10. At each impulse a circuit is formed from earth at 33 over off-normal springs 266, for relay 210 and vertical magnet 213 in series to raise the wipers 278, 279. The third digit sends impulses over a circuit for relay 208 and rotary magnet 212 in series to rotate the wipers. Two-step relay 209 operates its light armature 258 and at the end of the digit fully energizes, opening the rotary impulse circuit. Metering call in first zone. For calls in the first zone. wipers 278, 279 stop on contacts such as 282, 285, earth-connected and dead respectively. Relay 207 operates over wiper 278 and locks up over lead 63. Magnet 214 of hunting switch F also operates. When relay 21 operates. relav 202 is energized and locks up to lead 63. The time metering switch TMS is now stepped in a circuit including magnet 301. leads 289, 288, wiper 303. and back contacts of springs 324 and the like. When the wiper reaches a contact connected to a spring 325 which is in contact with the lug 333 on its cam 335, the switch stops, and when the lug 334 acts on said spring, relay 302 energizes over wiper 384 to operate light armature 336. When the lug 334 leaves spring 325, relay 302 fully operates over lead 290. When the pick-up cam PU closes springs 320 after relay 202 has operated, two-step relay 204 operates first partially, and then fully when springs 320 open. When springs 323 of cam 101 close, relay 203 operates to apply booster battery to conductor 62 so that the meter M registers one unit. When springs 320 are again operated, relay 205 pulls up in two stages, transferring control of relay 203 to the time charge cam C1. If springs 325 are again operated during the call, relay 203 again operates the meter M. Metering for calls in second and third zones. For the second zone, the switch ZM reaches contacts such as 281, 284, dead and earth-connected respectively, so that relay 206 operates instead of relay 207. Similarly for the third zone the contacts 280, 283 are both earth-connected so that both relays 206, 207 are operated. In this way. the initial and time cams IC2, C2, and IC3, C3 are brought into action for the respective zones, and as they have two and three projections respectively, the meter registers two and three units at a time for the second and third zones. release of connection. When the subscribers hang up, relay 22 releases and the train of switches is restored. Relays 23, 25 de-energize. removing earth from lead 63 so that relays 207 and 202, 204. 205. 302 release. Connection of idle zone marking switch to idle repeater. When the switch ZM is set and relay 209 operates, relay 211 is disconnected at contacts 260, 42, and releases relay 209. Magnet 214 of tinder-switch F is therefore de-energized and the switch advances one step. The release magnet of the switch ZM is now operated. Normally all the switches ZM are associated with repeaters, and there is no earth on the multiple lead 286, relay 216 being operated; similarly, if all the repeaters are busy, there is no earth on multiple lead 66<1>, and relay 216 operates. Assuming, however, that there is an idle repeater, when relay 211 releases, relay 216 is de-energized. Relay 217 is energized over wiper 274 which is earth-connected in the associated switches ZM. Magnet 219 now operates in a self-stepping circuit until it reaches the contacts of the switch shown, when relay 217 releases and relay 218 operates. Magnet 214 now steps the switch F in a circuit from earth on associated busy repeaters over wiper 251. When a free contact is reached, the switch stops, and relay 211 operates in series with magnet 214. Relays 216, 218 again operate, and relay 218 is cut out. Relay 201 in the seized repeater group now operates over wipers 251, 272 and locks up, completing an alternative earth for relay 211 when relay 218 releases.