Patent GB-658959-A (GB)
Title: Improvements in or relating to switching systems for telegraphic transmission
IPC: H04L12/54
Filed: 1947-07-04
Abstract: 658,959. Telegraph exchange systems. CREED & CO., Ltd. July 4, 1947, No. 17707. Convention date, July 8, 1946. [Class 40 (iii)] In a telegraph switching system in which message signals are received and stored at a station on a receiver combined with a transmitting device, each of a plurality of outgoing telegraph channels is associated with a different point of a rotary switch, each one of a plurality of manually operable selecting elements is individually associated with, but not directly connected to, a particular outgoing channel, and means operated by any one of the selecting elements controls the rotary switch to connect the transmitting device directly to the outgoing channel identified by the selecting element. General arrangement, Fig. 1. The messages received over a line, e.g. R1, may control an alternator circuit ALT so that alternate messages are received on printer perforators PP2, PP3 associated with separate transmitters TT2, TT3. The change from one printer-perforator to the other is effected by a message-end signal constituted by carriagereturn (CR), carriage-return (CR), " Letters." A switch may be actuated from its normal position so that all messages over the line R1 are fed to PP2 or PP3. Each printer-perforator comprises a tape feed-out arrangement TFO which ensures that at the end of the message, the tape is fed forward sufficiently for the last character received to reach the sensing pins of the tape transmitter. The transmitters are connected via two push-button assemblies PB each comprising 25 buttons, to rotary switches RS1, RS2 each provided with 25 contacts individually associated with sending channels L1 ... L25 and L26 ... L50. Each outgoing channel has an individual automatic numbering device NM1 ... NM25, NM26 ... NM50. On the establishment of a connection to the desired sending channel, the numbering device and the transmitter are connected via rotary switches RS3, RS4 ..., concentrator CC1, CC2 and distributers to a number of printers PTR which record the serial number of the message and the first line of the message, the monitoring printer being disconnected and freed to be taken into use by another sending circuit by the characters CR and line feed at the end of the first line of the message. Operation of the alternator, Figs. 2, 3.-The reception of CR, CR at the end of a message operates contacts 206 and the punch-hammer actuates the contact 209 to effect operation of a relay 201, which with switch 301 in its central position, causes signals to be transmitted to the printer perforator 304. In this condition of the alternator, the signal comprising CR, CR transfers the circuit back to the printer perforator 204. The receipt of CR operates contact 206 and a circuit is completed for a relay 300 which energizes. Whilst contact 209 is closed by the punch-hammer the left-hand winding of relay 211 is short-circuited, but when contact 209 opens, relay 211 operates and relays 300, 211 lock up. If a second CR return signal is received, a circuit is completed for relay 201, which locks up over the back contact of relay 216. At contacts 202, 217 the relay applies positive battery to selecting magnet 203 and transfers the line circuit to magnet 303 of the printer perforator 304. The closure of contact 209 releases the locking circuits of relays 211 and 300 which de-energize. When perforator 304 is in operation the first CR return signal operates contacts 306, relay 300 is again operated and the relay 211 is energized after the punch hammer contacts have opened. When the second CR signal is received, contacts 306 are again closed and a circuit is established to relay 219. Simultaneously with the operation of the relay 219 a circuit is closed from the closed punch hammer contacts 309 to a relay 305 which places a short-circuit on the winding of relay 213. When contacts 306, 309 open the short-circuit around the coil of relay 213 is removed and a circuit is completed through coil of relay 219 and relay 213 which energizes and operates relay 216 opening the locking circuit of relay 201 which releases and restores its contacts to the position for passing signals to the printer-perforator 204. If the first CR signal is followed by a signal other than CR, contact 206 is not closed, but the punchhammer contact 209 is closed, opening the locking circuits of relays 300, 211 and restoring the circuit to normal condition. The movement of the switch member 301 to its upper or lower positions opens contacts 302, 311, respectively, and by disabling the alternator circuits causes the received messages respectively to be fed exclusively to perforator 204 or 304. If the switch 301 is moved during the reception of a message, succeeding messages are passed to the printer-perforator corresponding to the position to which the switch has been moved. Tape feed-out arrangement.-At the end of a message, and if no further messages are received by the printer-perforators within a predetermined time, the message-end signals are effective to feed tape to the transmitter so that the final perforated signal is advanced to the sensing pins of the transmitter. The tape feed out is controlled by the CR contacts 207, punchhammer contacts 208, 210 and contacts 221 which are normally closed but are opened when the " Letters shift" signal is received. Relay 222 is normally energized over contacts 221 and when the first CR signal is received, a circuit is completed for the left-hand winding of relay 223 which operates. At contact 210 a circuit is closed for the right-hand winding of relay 223-the windings being in opposition and the resistance 226 being greater than resistance 224. Relay 223 completes a circuit for relay 227 over resistances 228, 229 to tongue of relay 203 and positive battery. Relay 227 operates and locks up over a circuit independent of relays 222, 223. If a second CR signal is received, the relays are unaffected, but if a signal other than CR is received, the closure of contact 210 provides current through the right-hand winding of relay 223 which is greater than that through resistances 224 and 232 and relay 223 releases, applying ground at released contact 233 to the winding of a relay 234 which is thereby prevented from operation if the line 404 leading to a tape-controlled contact 402, Fig. 4, is grounded due to a taut condition of the tape. If the second CR signal is followed by the " Letters " signals, the contact 221 is opened, releasing relay 222, but relays 223 and 227 remain energized. If a second " Letters" signal were received, the start impulse would de-energize relay 227, but contact 221 would be closed temporarily and re-energize relay 222 which would reoperate relay 227 and leave this relay energized when the " Letters " combination again opened contact 221 and released relay 222, so that relays 223, 227 are energized at the end of one more " letters shift" signals. When the contacts 402, Fig. 4, are closed by the taut condition of the tape, a circuit is closed over line 404 and the windings of relays 234, 227 to closed contact of the relay 203. The operation of the relay 234 energizes magnet 237 controlling the tape feed-out, and at its left-hand contact releases relay 227 which in its turn releases relay 234. The tape feed-out mechanism of the printer-perforator is so arranged that should another message be received whilst a tape feed-out operation is in progress, the tape feed-out will be interrupted and the tape 236 be perforated in accordance with the signals being received. Operation prior to selective operation. The tape is stepped through the transmitter, until a taut-tape condition is reached, by the operation of a clutch magnet CM operated over a back contact of a relay 501, Fig. 5, and the closure of contacts 8 of the distributer energizes a stepping magnet SM over a back contact of a relay 408, a conductor 702, back contact of a relay 701, Fig. 7, and conductor 413. When a taut-tape condition is reached, contacts 409 open and break the circuit of the clutch-magnet CM. When a further message is received, tape is fed through the transmitter 403 until a character other than letter shift sensed by the pins 1 ... 5 effects the operation of a relay 408 which opens the circuits of the clutch magnet CM of the distributer 406 and the stepping magnet of the transmitter 403. Relay 408 also effects the release of a relay 601, Fig. 6, and illuminates a lamp 602 which indicates to the operator that a message is waiting to be switched. The sending circuit of the message. is indicated by the message tape and the operator presses the appropriate button of the banks 706, 806. The upper contact members are connected to the contacts of the fifth level of the rotary switches 707, 807 and the bottom contacts are connected to potential through the released contacts of relays 708, 808. The operation of a button of the bank 706 removes ground from the associated contact of the fifth level and, for example, by energizing relay 708 cuts off battery from the buttons of the bank 806. Relay 708 completes a circuit for the magnet SM of the rotary switch 707 which steps until it finds the ungrounded contact. At this stage relay 703 operates and opens the circuit of the lamp 602. At the first level a conductor 714 is connected to a conductor 713 to illuminate a stand-by lamp 415. Conductor 715 is connected to a conductor 718 leading to a contact of relay 818 as yet unoperated. The conductor 716 is connected to a conductor 719 leading to a tongue of relay 407 which on operation extends the circuit to No. 6 contact of the distributer 406. The conductor 717 is connected over the coil of relay 818 and conductor 819 to an interrupter 606 and is also connected over relay 904 and back contact of relay 907 to positive battery. If the sending circuit is free, relay 818 is operated when the rotating arm 607 of the interrupter 606 engages the contact assigned to the calling selective switc