Patent GB-191316696-A (GB)
Title: Improvements in Telephone Machine Switching Systems.
Filed: 1913-07-21
Granted: 1914-07-21
Abstract: 16,696. Western Electric Co., [Woodward, F. T., (acting for Western Electric Co.)'. July 21. Automatic exchange systems.-In a two-wire system, the setting, change-over, and restoration of a number of switches are controlled by a relay set comprising one slow-acting and two quick-acting relays, one of the quick-acting relays being included in the line circuit and controlling the slow-acting relay. The invention is described as applied to the operation of a register controller. In the system described, a calling-line 41 is connected by a call-finder to a connecting-circuit associated with a register-controller, which controls the operation of a line selector in selecting the wanted line 42. The circuits of the call-finder and selector are controlled by a sequence switch, represented by its motor magnet 20 and the various springs shown above the dotted line, and the circuits of the register-controller 77, 97 are controlled by a sequence switch, represented by its motor magnet 80 and the contacts below the dotted line. The register-controller is of the kind described in Specifications 26,079/10 and 21,259/11. Call-finder. When the subscriber 41 removes his receiver, his line relay 43 puts selectable potential upon his test terminal 47, and energizes a relay 44, which closes the circuit of the motor magnets 52 of all idle call-finders over contacts 25, 26. The call-finders rotate until one finds the calling-line, whereupon its relay 50 energizes over contacts 27, 29, wiper 48, and relav 44. The relay 50 brings its low-resistance winding into this circuit to prevent any other call-finder from making connexion with the line. and as soon as the wipers are accurately centred, the relay 51 is energized and opens the circuit of the motor magnet 52, closes that of the holding-magnet 53, and moves the sequence switch 20 into its fourth position. Adjustment of register-controller. The stepping-relay 91 of the register-controller is then energized over contacts 33, 34 and the calling line, and moves the sequence switch 80 into its second position. At the first interruption of the line circuit by the impulse sender, the relay 91 energizes a quick-acting relay 92 but the interruption is not sufficiently long to energize a slow-acting relay 93 over its right-hand winding and contact 88. The relay 92 locks up, so that when the line circuit is again closed, the relay 91 closes a circuit through the stepping- magnet 76 of the tens register 77, left-hand winding of relay 93, and right armature of relay 92. Successive interruptions of the line circuit are similarly repeated to the magnet 76, but the relay 93 is still not energized, as the period of closure, as well as the period of interruption, of the line is insufficient. At the end of the impulses, the line circuit is closed sufficiently long for the relay 93 to energize, thereby moving the sequence switch 80 to its fourth position, the locking-circuit of relay 92 being opened as it passes through the third position. The second set of impulses is similarly repeated to the stepping-magnet 96 of the units register 97, and at the close the relay 93 is again energized, and moves the sequence switch 80 to its sixth position. Line selector. The selection-controlling circuit is then closed through relays 56, 94, contact 87, and the armature of relay 95. The relay 94 closes the circuit of the restoring-magnet 78 of the tens register over contact 85, and the relay 56 moves the sequence switch 20 into its fifth position, closing the circuit of the power magnet 57 of the brush-chooser. As the tripping-spindle rotates, the relay 94 is intermittently shortcircuited over contacts 38, 69, and the impulses are repeated to the magnet 78. When the tens register 77 reaches normal, the relay 95 is energized and (1) opens the circuit of the relay 56, thereby moving the sequence switch 20 into its sixth position, and disconnecting the motor magnet 57, and (2) moves the sequence switch 80 into its eighth position, in which the selection-controlling circuit including relays 56, 94 is again closed. The relay 94 closes the circuit of the restoring-magnet 98 of the units register 97, and the relay 56 moves the switch 20 into its seventh position, closing the circuit of the brush carriage motor magnet 59. After the selected set of brushes has been tripped, the relay 94 is intermittently short-circuited over contacts 38, 62, and when the units register 97 reaches normal, the relay 95 is again energized, moving the switch 80 into its ninth position, and opening the circuit of relay 56, which energizes the holding - magnet 63 and moves the switch 20 into its eleventh position. Restoration of register-controller in the event of premature disconnexion of calling subscriber. If the tens register is off normal when the switch 80 reaches its ninth position, an interrupter 75 is connected over contact 85 to the resetting-magnet 78, and wlien the register 77 reaches normal, the relay 95 is energized and moves the switch 80 into its tenth position, in which the interrupter 75 is connected to the resetting-magnet of the units interrupter. Busy test and busy release. As the switch 20 passes through its tenth position, the circuit of the test relay 50 is completed over contact 28, left-hand winding of relay 50, relay 51, and the armature of the calling subscriber's supervisory relay 64. If the wanted line is busy, the relays 50, 51 are not energized, and the sequence switch comes to rest in its eleventh position, in which the power magnet 59 is energized over contacts 25, 26, and the armature of relay 56. The brush carriage is returned to its normal position, in which the relay 56 is energized over contacts 38, 60 and moves the sequence switch into its fifteenth position, wherein a busy generator is connected over contact 32 to the calling line. The release is completed when the calling subscriber hangs up. Ringing-current. If the wanted line is idle, the relay 50 is energized in series with the cutoff relay 65, and closes a low-resistance circuit through its right-hand winding, thus marking the line engaged. In the eleventh position, the relay 51 moves the sequence switch into its twelfth position, in which ringing-current is supplied through a marginal relay 66 to the called line. When the subscriber replies, the relay 66 is energized and moves the switch 20 into its fourteenth or talking position, the microphone supply circuit including the supervisory relays 64, 67. Release. When the calling subscriber hangs up, the relay 64 moves the switch 20 into its sixteenth position, in which the calling line is entirely disconnected and is free to make or receive a further call. As soon as the called subscriber hangs up, the relay 67 moves the switch 20 into its seventeenth position, and if the register-controller has reached its normal position, a further circuit is closed over contacts 23, 74 which moves the switch 20 into its eighteenth position, in which the brush carriage motor magnet 59 is energized over contacts 25, 26, and the armature of relay 56. When the brush carriage reaches normal, the relay 56 is energized and arrests the carriage. Premature disconnexion. The contacts of the sequence switches 20, 80 are so connected that the apparatus is returned to normal if the calling subscriber hangs up prematurely. Since the initial circuit of the test relay 50 includes the front contact of the supervisory relay 64, if the calling subscriber hangs up while the switch 20 is passing from the seventh to the eleventh position, release is effected in the same way as in the case in which the wanted subscriber is busy. If the subscriber hangs up while the switch 20 is in any of the positions two to seven, the relay 91 closes a circuit through the righthand winding of the slow-acting relay 93, which moves the switch 80 to its ninth position, from which it is returned to normal in the manner previously described.