Patent GB-191417590-A (GB)
Title: Improvements in or relating to Telephone Systems.
Filed: 1914-01-24
Granted: 1915-04-08
Abstract: 17,590. Automatic Telephone Manufacturing Co., and Sperry, A. B. Jan. 24. Semi - automatic ex- 'change systems. - An operator is provided with two impulse-sending machines controlled alternately by a single key-set, and each trunk outgoing from her position is provided with relays for connecting it to either sender. The automartic switch circuits are of the two-wire type described in Specification 1298/10, and the sender shown in Fig. 4 is of the kind described in Specification 5249/13. The digits of the wanted number are recorded on a pin-disk 113 by successively energizing the corresponding magnets 62<1> &c. by means of a row of ten keys 61<1> &c. The disk 113 is then set in rotation by depressing a starting-key 114, and impulses are sent by a wheel 116 intermittently opening springs 117 in the circuit 118, 119, a pause in the flow of impulses being effected by the energization of a relay 121 and magnet 122 each time the springs 120 are closed by the passage of one of the selected pins. A relay 126, energized by the depression of the starting-key, disconnects the keys from the sender shown and connects them to the leads X of the second sender, on which a second call can be recorded while the first sender is dispatching its impulses. If a wrong number is set up, a key 177 is pressed, which causes a switch-over to the second sender without any impulses being dispatched. The first sender can be connected with a trunk circuit, such as that shown in Fig. 2, over the leads 118, 119 129, 130, and the second sender over corresponding leads W, one or other sender being taken into use by energizing a relay 57 or 56. The operations of making a connexion in the system shown are as follow. A call from a manual subscriber A, Fig. 1, for a subscriber on an automatic exchange is answered in the usual way by an A-operator, who communicates over an order wire (not shown) with a B- operator at the same exchange and plugs into an outgoing automatic trunk 44, 45 allotted by her. This energizes a relay 54, Fig. 2, at the B-operator's position, and a relay 131 lights the trunk busy lamp 51. The B-operator, whose business it is to control the automatic switches which complete the wanted connexion at the distant end of the trunk, throws a kev K<3> to the right, energizing a relay 187, which locks itself up until the connexion is eventually released, and also energizing one of the relays 56, 57 to connect one of the senders to the trunk. If at this moment the relay 126, Fig. 4, were in an energized condition, the relay 56 would be energized, but as the relay 126 is assumed to be in a deenergized condition, the relay 57 is energized, its circuit being completed over the wires 129, 130 and through a relay 156, which lights a lamp 157 to indicate that the sender shown in Fig. 4 is in use. The relay 57 locks itself in a circuit independent of the relay 126 and connects the outgoing leads 47, 48 to the impulse circuit 118, 119. The operator now, by means of her key-set 61<1> &c., sets up the wanted number on the pin - disk 113 and depresses the starting- key 114. A locking- frame 158 is shifted by the number keys and detained by a detent 160 until the starting - key is pressed, and in the interval lights a lamp 172. The starting - key energizes a relay 162, which closes circuits through the motor 115 and relays 165, 166, and also energizes a relay 128, which energizes the relay 126. The relays 128, 126 lock themselves so as to be independent of each other, but the relay 128 is de-energized when the key 114 rises again, while the relay 126 remains energized. If the key K<3> of another trunk is now thrown, the second sender is connected to it, and the number keys may be operated to record the wanted number on this sender over the leads X. The starting-key 114 is then again depressed, and this time energizes the relay 127 instead of the relay 128, and the relay 127 restores the relay 126 to its deenergized condition. It will be seen that the relays 128, 127 control the alternate energization and de-energization of the relay 126 to put the two senders alternately in action for successive calls. Alternatively, this may be effected, as described in the Provisional Specification, by the use of separate interlocking starting-keys for the two senders. Returning to the original call, the armature of the relay 162 is locked mechanically bv the movement of the disk 113, but when this disk has completed its rotation, the contact 164 is opened and the motor 115 and relays 165, 166 are de-energized. The relay 166 is slower to de-energize than the relay 165, so that on the one hand an impulse is sent through a counter 185, and on the other hand the circuit 129 is momentarily opened so as to unlock the relay 57, Fig. 2. In the meantime, the impulses in the circuit 118, 119, 47, 48 have operated a connector as described in Specification 1970/14 to select and ring the wanted line. Supervisory signals. The key K<3> being restored, a relay 55 is energized in a circuit which extends through the called line and back through an inductance 191. The relay 55 open-circuits a lamp 53 and cuts the lowresistance right-hand winding of the relay 54 in parallel with the high-resistance left-hand winding, reducing the resistance of the circuit 44, 45 sufficiently to energize a relay 91, Fig. 1, which cuts out a lamp 39. When the calling and called subscribers hang up their instruments, the relays 35, 55, 91 are de-energized and the supervisory lamps 38, 39, Fig. 1, light up. Release. The A-operator withdraws the plugs P, P<1>, and the relay 54 de-energizes the relay 131, which lights the lamp 52. The lamp 53 has already been lit by the de-energization of the relay 55, and the B-operator, seeing both lamps alight, presses the release key K' to unlock the relay 187. This de-energizes the lamps 52, 53 and open - circuits the outgoing conductors 47, 48, so as to release the automatic connexion. Busy signal. If the wanted line is engaged, a busy tone signal is intermittently sent back over the trunk 47, 48, and in the intervals a battery connexion is made to the conductor 48, as described in Specification 1970/14, to energize the' relays 55, 91 and flash the lamps 53, 39.