Patent GB-117441-A (GB)
Title: Improvements in or relating to Automatic Telephone Systems.
IPC: H04Q3/62
Filed: 1918-03-21
Abstract: 117,441. Automatic Telephone Manufacturing Co., (Assignees of Nelson, M. L.). July 9, 1917, [Convention date]. Automatic exchange systems.-In a system for private installations, a special code-ringing and intercommunicating circuit is provided whereby certain officials may be reached when they are absent from their offices on business in other departments. Special belis in each department are connected in multiple across a common signalling circuit, which is controlled by an automatic code-ringing equipment in accordance with prearranged codes, one of which is assigned to each official. The code-ringing equipment is connected to a particular set of terminals in the connectors, and a person, wishing to communicate with an official who is absent in some unknown department, calls the number assigned to the code-ringing equipment. One or more additional digits are then called in order to set the ringing-equipment for the code ring of the particular official wanted, whereupon all the special bells are rung in parallel according to this code. Upon hearing his characteristic call, the wanted official goes to the nearest telephone and calls) a number corresponding to a second set of connector terminals, which are connected to the first set, so that conversation mav take place over the circuit thus established. The invention is described as applied to a system in which a calling party A is connected by a rotary line switch C to an idle connector E, the wipers of which are shown engaging the terminals 93, 94, 95 assigned to the code-ringing equipment, Fig. 2. The called party, responding from the station A<1>, is connected by switch C<1> to an idle connector E<1>, the wipers of which are shown adjacent the second set of terminals 193, 194, 195 previously referred to. Terminals 93, 195 and 95, 193 are connected by leads 76, 77, but the test terminals 94, 194 are connected to the ringing-equipment by separate leads. The ringing-equipment, Fig. 2, comprises a rotary code-selecting switch M with four wipers 115 - - 118 and a rotary ringing- switch N with two wipers 119, 120, of which the wiper 120 controls a relay 122 adapted to bridge a ringing-generator S<1> across the leads 123, 124, having bridged bells R<1>, R<2>, R<3> &c. in the various departments. The operation in further detail is as follows :- Rotary line switch C, Fig. 1. When the calling party removes his receiver, his line relay 15 closes a circuit through the cut-off relay 16 and the stepping-magnet 17. If the wipers are already in connexion with the terminals of an idle connector, the cut-off relay 16 energizes and extends the calling-line to the relay 40. If, howover, the wipers engage the terminals of an engaged connector, the cut-off relay is short-circuited over armatures 22, 19 and the test wiper 31, and the stepping-magnet 17 moves the wipers round until an idle connector is found, when the cut-off relay is energized as before. The resisttance of the cut-off relay is such that the stepping-magnet cannot energize in series with it. Operation of conector E for normal call. The line relay 40 energizes the release relay 41 in the usual way, and the first set of selecting-impulses are repeated to the vertical magnet 48 and slow-release relay 42, the first impulse passing over off-normal springs 59, 58, and succeeding impulses over springs 59, 57 and the attracted armature 53. When these impulses cease, the relay 42 de-energizes so that the next set of impulses is repeated over armatures 51, 52, 53, slow-release relay 45, and armatures 72, 54 to the rotary magnet 49. By attracting its armature 68, the relay 45 provides an alternative circuit for the rotary magnet. should the relay 43 be momentarily energized due to the test wiper 91 passing over grounded test contacts. Busy test and busy signal. The relay 45 disconnects the test wiper 91 from the lower winding of the switching-relay 46 and connects it over resistance 47 and armature 60 to the upper winding of the combined test and answering bridge relay 43. If the selected line is busy, its test terminal is earthed, and the relav 43 is energized, thereby (1) finally disconneting the rotary magnet 49, (2) opening at its armature 55 a contact in the circuit of .the lower winding of relav 46, (3) connecting the busy generator Q over armature 56 to the calling line, and (4) preparing at its armature 55 a locking circuit for itself which is completed a moment later when the relay 45 de-energizes, and extends from ground G<3>, lead 79, armature 55, springs 71, 70, and resistance 47 to the upper winding of the relay 43. The connexion is released when the calling party hangs up. Supply and control of ringing-current for ordinary call. If the selected line is idle, the relay 46 is energized over its lower winding and the test wiper 91 when the relay 45 de-energizes and (1) by attracting its armature 73 completes a locking circuit through its upper winding, and directly earths the test wiper over lead 79, (2) by attracting its armature 72 prepares a circuit for the lower winding of the ringing cut-off relay 44, and (3) connects the ringing-generator S over springs 65, 67, and armatures 63, 74, to the selected line, the circuit returning through the lower winding of relay 44, armatures 72, 54, and the rotary magnet 49. When the called subscriber replies, relay 44 is energized, disconnecting the ringing-current, and completing the talking circuit shown in heavy lines. The battery connected to the back contact of the armature of relay R is in series with the battery connected to the rotary magnet 49, thus ensuring the energization of the cut-off relay 44 when the called subscriber answers. A ringing-signal is given to the calling subscriber through the upper winding of relav 44. Microphone current is supplied to the called line through the windings of relay 43. Operation of connector for special call by the code-ringing equipment shown in Fig. 2. As previously stated, the code-ringing equipment is connected to a particular set of terminals in the connectors, in the case assumed to the terminals corresponding to the call number 70, and a cam 75, Fig. 1, on the connector shaft is arranged to shift spring 67 from spring 65 to spring 66, thus disconnecting the ringing-generator S and preparing a circuit over which a further set of impulses is transmitted to operate the code-selecting switch M, Fig. 2. A calling party, desiring tn make a special call, first calls the number 70, thus operating the connector in the manner described to extend connexion to the terminals 93, 94, 95 of the code-ringing equipment. Operation of code-ringing equipment. If the equipment is busy, the calling narty receives a busy signal as before, but if the equipment is idle, the switching-relay 46 energizes over its lower winding and the test wiper 91 in series with a relay 102, Fig. 2. The calling party then transmits one or more further digits in accordance with the code number of the wanted official. These impulses are repeated by the line relay 40 over armatures 51, 52, 53, springs 66, 67, armature 74, wiper 92, lead 98, and relay 103 to the stepping-mganet 113 of the codeselecting switch M, thus setting the wipers 115 - - 118. The eleventh and twenty-first contacts engaged by the wiper 115 are not multipled to the other contacts, so as to permit the wiper to be moved ten or twenty steps without starting the ringing-switch N. When the impulses cease, the relay 103 de-energizes, completing a circuit over wipers 115 for the relays 101, 104. Relay 101 opens the circuit of the stepping-magnet 113, and the relay 104 closes the circuit of the stepping-magnet 114 of the ringing-switch N, which in turn opens the circuit of the relay 104. A vibratory action is thus set up between the relay 104 and the stepping-magnet, whereby the wipers 119, 120 are advanced step by step and this action continues as long as the ground potential is maintained on the junction 137. At its second step, the wiper 120 energizes the relay 122, which connects the generator S<1> across the bridged bells R<1>, R<2>, R<3> in the various departments. The contacts engaged by the wiper 120 are so connected to the wipers 116, 117, 118 and their contacts, that during the rotation of the wiper 120, the relay 122 is energized for long and short periods according to the setting of the wipers 115 - - 118. The code ring is repeated during each rotation of the wiper 120. Operation when called party responds to the call. When the called party hears his characteristic call, he goes, to the nearest telephone A<1> and calls the special answer number 79 whereby the connector E<1>, operating in the manner previously described, moves its wipers to the special terminals 193, 194, 195, which are connected to the terminals 93, 94, 95 corresponding to the special call number 70. When the slowrelease relay 186 de-energizes at the end of the rotion, a circuit is closed from ground G<10>, over lead 182, armature 183. lower winding of switching- relay 185, armature 179, test wiper 191, lead 97, and relay 100 to battery. Relay 185 energlzes and (1) locks up over its upper winding and lead 182, (2) closes an energizing circuit for' the ring- ing cut-off relay 44 of connector E, which extends from ground G<11> or G<12>, generator S or battery. lead 176, springs 175, 174, armatures 173, 177, wiper 192, lead 77, wiper 90, lower winding of ringing cut-off relay 44, armatures 72, 54, and the rotary magnet 49. The ringing cutoff relay 44 locks up over its upper winding and extends the calling line to the wipers 90. 92. The ringing cut-off relay 187 of connector E<1> is then energized over a circuit from ground G<3>, lead 79, armature 61, lower winding of the answering bridge-relay 43, armatures 63. 74. wipers 92, 190, lower winding of relay 187. and armatures 178, 172 to the rotary magnet 171 and battery. Relay 187 o