Patent GB-186967-A (GB)
Abstract: 186,967. Western Electric Co., Ltd., and Polinkowsky, L. June 10, 1921. Automatic exchange systems.-In an automatic call-distributing system of the type in which operators are classified in degrees of availability according to the number of calls they have in hand, and, in which incoming calls are passed to those operators who are more available, whilst when all positions are equally loaded, each position is made available for one further call, means are provided by which an operator's position which has been classified as having received a definite number of waiting calls remains so classified until all the calls have been cleared. In the system described, calls are distributed uniformly amongst the operators until each has three calls in hand after which further calls are distributed indiscriminately. When a call is passed to a position, that position is made unavailable to all other calls for a definite period of time. A calling line 1, 2 is connected over a first line-finder 26 - - 29, Fig. 1, and a second line-finder 253 - - 256, Fig. 2, associated, with an operator's position, Fig. 3, to a first group selector shown at the right of Fig. 2. The second line-finder hunts for an idle registering-equipment and the required number is then set up on the operator's keyboard set which controls the selected registering-equipment, in the usual manner. The calling lines are arranged in groups to each of which a group of first-finders, divided into several subgroups, has access, the sub-groups being connected to different second-finders. The secondfinders are also arranged in groups and three of these groups form a super-group. Each group contains a number of sub-groups each containing, for example, three second-finders and each operator is provided with one or more of these subgroups from a number of super-groups. The arrangement is such that only those first-finders with which are associated available second-finders are permitted to search for the calling line. When an operator's position is occupied, a relay 300 is energized in series with the transmitter 302 of the operator's speaking set, and as long as the position is free, relay 303 is energized in a circuit 382, 383, 305, 397, 384. 370 and locks up over contact 395 Timing sequence switch 320 which controls the contacts enclosed within the lower dotted rectangle normally :rests in either its 6th, 12th, or 18th position in which the above circuit for relay 303 is closed at contact 305. Relay 303 energizes relays 312, one of which is provided for each two sub-groups of second-finders, and also drives the switch 320 into its next position, say its first position. Relays 319, 329, 339, each individual to a group of second-finders, energize over a number of parallel paths comprising the armatures of relays 312 in their operated position and contacts 226 in each second-finder circuit which has its controlling seauence switch 220 in its 1st (normal) position. Relays 319, 329, 339 are thus energized as long as there is at least one free operator's position and an idle second-finder available at that position. When a call is made over a subscriber's line 1, 2, relays 3, 4, 5 energize and close circuits 6, 10, 318 in all those subgroups of first-finders which have access to the calling line and which are associated with available second-finders. If there are no available second-finders, relay 319 is de-energized and this circuit is not closed. Relays 6 energize the power magnets 20 of the first-finders in these subgroups, and when the brushes 26 - - 29 reach the calling line, the test relay 30 energizes and disconnects the power magnet 20 in known manner. Relay 33 energizes in series with the holding magnet 31 and energizes relay 34 which closes circuits 35, 333, 234, 236, 230, 238, 240, 242, 227, energizing relays 230 in all second-finder circuits which have their switches 220 in the 1st position. Relays 231 energize in parallel branch circuits 35, 236, 231, 243, 245. Power magnets 247 energize over circuits 248, 250, 252, and when the brushes 253 - - 256 reach the terminals of the first-finder to which the calling line is connected, the test relay 241 energizes in the usual manner and breaks the circuit of relay 230 which de-energizes to drive the switch 220 into its 3rd position, in which the register-selecting sequence switch 262 hunts for an idle register. On the de-energization of relay 230, relay 363 also energizes in series with the holding magnet 207 in a circuit 330, 207, 258, 250, 252, and breaks the locking circuit for relay 303 which de-energizes, breaking the circuits of relays 312, thus marking the whole position busy, and completing a circuit 316, 314, 353 to drive the timing switch 320 into its 2nd position. The switch 320 is moved forward stepby-step from its 2nd position under the control of the relay 335 which is alternately energized and de-energized by the interrupter 336, until the switch 320 reaches its 6th position, when the circuit for relay 303 is again closed at contact 305; so that until the definite time required for this stepping movement has elapsed, the relay 303 cannot under any circumstances energize and the position is completely inaccessible during this time. Whilst the switch 262 is hunting for an idle register in the 3rd position of the switch '220, relay 309 energizes and lights the first-waiting-call lamp 375 but as soon as the switch 262 has found an idle register, the switch 220 moves to its 4th position, the relay 309 is disconnected, the circuit for relay 303 is completed and the position marked idle as before. In the 2nd and 3rd positions of the switch 220 a calling lamp 323 is continuously lit, but when the switch passes to its 4th position, the lamp is intermittently lit over the interrupter 233, indicating that an idle register has been found. If the switch 262 has not completed the selection of an idle register when further calls arrive, the relay 303 cannot energize so that the calls are passed to other positions as long as any are idle. When all the operators associated with a super-group of secondfinders are engaged, relays 319, 329, 339 are all de-energized and, on a further call coming in, a circuit 43, 344, 346, 348, 340, 341 is completed energizing relays 340 and 341 which close an alternative energizing circuit 305, 397, 384, 359, 322, 223, 227 for the relay 303 as long as any of the second-finders are idle. Relay 303 energizes and locks up, breaks the circuit of relays 340, 341, and the position is available to receive a second call. When a second call arrives at a position at which one call is already in hand, for example, in which the relay 309 is energized, relay 303 relapses as before and relav 308 energizes in a circuit 3@0, 308, 395 lighting second-waiting- call lamp 386. Relay 308 also opens the main circuit for relay 303 at the armature 384, preventing it from energizing until all positions have two calls in hand, and energizes relay 380 to prepare a circuit for relay 307. When two calls have been passed to each position and a further call arrives, relays 319, 329, 339 energize relays 340, 341 as before, but relay 303 does not energize and after a short time, slow-acting relay 350 energizes relays 354, 355 to close a contact 357 which short-circuits the opened contact 384. Relay 303 energizes and each position can then receive a third call. When such a third call arrives at a position, relay 307 energizes in a circuit 390, 307, 395 lighting the third-waiting-call lamp 399 and opening the circuit of the relay 303 at a third point 397. When all the positions have three calls in hand, relays 354, 355 energized as before cause a slow-acting relay 360 to energize relays 365, 366 closing a contact 367 which short-circuits the opened contact 397 in the circuit of the relay 303. This relay can now energize and the position is available to receive further calls. Relav 307 locks up over a contact 390 of relay 309 which remains energized as long as any second-finder is hunting for an idle register, so that the lamp 399 will remain alight and the operator will be classified as having three waiting calls until all the calls have been cleared.