Patent GB-105266-A (GB)
Title: Improvements in Semi-automatic Telephone Exchange Systems.
Filed: 1916-04-11
Abstract: 105,266. Western Electric Co., Deakin, G., and Polinkowsky, L. April 11, 1916. Semi-automatic exchange systems.-In call-distributing systems in which a calling-line may be extended to any one of a number of operators' positions, if idle, the busy or idle condition of the operator's position is independent of the condition of any particular call extended to such position, but is determined by means, such as a timing- device, associated with the position and responsive to the extension of a call to the position. The period for which the position is maintained busy is less than the time normally required by the operator to attend to a call, provided that Do other call is awaiting attention on the position; but if there are one or more waiting calls the period for which the position is made busy is increased according to the number of such calls. In the system described, a calling-line 3 is connected by line-finders 4, 16 to a connecting-circuit 17 on an idle operator's position, and this connecting-circuit is extended by the switch 29 to a registering and controlling equipment. Each operator's position is provided with sequence switches 70, 80, 90, the contacts of which are included in the areas indicated by dotted lines. When a subscriber calls, his line relay 5 puts selectable potential on his test terminals 6 in the first line-finders and energizes a starting-relay 7, which causes idle finders to rotate under the control of relays 9, 12 in known manner. When the calling-line is found and the brushes are properly centred, the relay 9 open-circuits the power magnet 8, puts selectable potential on the terminals 21 in the second line-finders, and energizes a common starting-relay 15. The relay 15 controls a group of line-finders, having access to the first line-finders, on several operator's positions. If the operator at the position shown in Fig. 1 is idle, her sequence switch 70 is in its first position, closing contact 72, so that the relay 15 closes the circuit of relays 18 of all the second line-finders 16, having access to the first linefinders, on this operator's position. The relays 18 energize the power magnets 20, rotating the second line-finders under control of relays 19, 24 in known manner. When the terminals of the first line-finder are reached and the brushes properly centred, relay 19 is energized, disconnecting power magnet 20, moving sequence switch 60 into its fourth position, and energizing a relay 26, which starts the operator's sequence switch 80, moving it into its fourth position. The switch 80 causes the sequence switch 70 to move into its twelfth position, thus marking the position busy to other calls by opening contacts 72, 72', &c. in the circuits controlled by the starting-relays 15; 15<1> corresponding to various groups of first linefinders. In its fourth position, the switch 80 causes the sequence switch 90 to move through a complete revolution, and the switch 90, as it passes through its eighteenth position, moves the switch 80 into its fifth position. By this time, as the operator has been assumed to be idle, the connecting-circuit 17 will have been connected by switch 29 over contacts 66. 67, 68 to an idle registering and controlling equipment, and the switch 60 will have therefore been driven out of its fifth position, opening contact 66, so that the relays 27, 28 will both be de-energized. The switch 80 is therefore driven direct from its fifth to its tenth position, the circuit being closed at first over the back contact of relay 28 and upper contact 86, and then over the back contact of relay 27 and lower contact 86. In its tenth position, switch 80 causes the switch 90 to make a complete revulution, moving switch 80 into its eleventh position, in which the switch 90 makes a further revolution, moving switch 80 into its twelfth position, from which it moves back to normal, closing switch 84, which moves switch 70 to normal, rendering the position free to receive further calls. The switch 70 has been out of its normal position, and the position marked busy, for a period during which the switch 90 has made three complete revolutions. If, however, the operator is still engaged with a previous call when a second call is received on the position, the switch 29 continues to hunt for an idle registering-equipment, and the relay 27, but not the relay 28, is energized in series therewith, so that the switch 80, although it passes through its fifth, sixth, and seventh positions under control of relay 28, will be arrested in the eighth position and can only move step by step into its twelfth position, one step for each revolution of the switch 90. Two additional revolutions of the switch 90 are thus inserted before the switch 80 moves the switch 70 to normal, and therefore the position is engaged for a longer period. If, however, the operator has two calls awaiting attention when a third call is received, two switches 29 will be in circuit with the relays 27, 28, in which condition both of these relays are energized, and the switch 80 is arrested in its fifth position and can only move step by step into its twelfth position, one step for each revolution of the switch 90. Five additional revolutions of the switch 90 are thus inserted before the switch 80 moves the switch 70 to normal, and therefore the position is engaged for a still longer period. In the event of the position becoming free, or being engaged by one call instead of two, while the switch 90 is making its additional revolutions, the switch 80 moves at once to the corresponding position so that certain revolutions are suppressed. Fig. 2 shows a trunking-scheme for three operators' positions. The first three groups of line-finders (two being shown in each group) have their trunks terminating in second line-finders 16, the second three groups are connected to line-finders 50, and the third three groups to linefinders 51, the second linefinders 16, 50, 51 being arranged at different positions, as shown. The starting-relays 15, 15<1>, 15<x>, common to the several sets of groups of first line-finders respectively, earth leads connected through contacts 72, 72<1>, 72<x> respectively (on the sequenee switches 70 of each position), to the relays 18 controlling the corresponding second linefinders. For example, the relay 15 closes circuits through the contacts 72 of all idle positions for the relays 18 controlling the line-finders 16 that have access to the group of linefinders 4 to which the relay 15 belongs.