Patent GB-189765-A (GB)
Title: Transmitting and receiving apparatus for type-printing telegraphy
IPC: H04L13/12
Filed: 1922-11-10
Abstract: 189,765. Lindet, P. Dec. 1, 1921, [Convention date]. Type-printing telegraphs.-I n typeprinting telegraphy systems, each character is signalled by a sequence of impulses, all of the same sign, the characters being differentiated by the number of impulses and by their timing in the interval allotted to a single character. The operation of any character key at the sending-station sends an impulse to line which operates a master relay at each station. The master relav causes a set of relays (say five) to be energized successivelv at both stations. At the sending-station, these sequence relays send impulses to line through one or more of five switches operated according to the character transmitted; and at the receiving-station, these impulses pass selectively through one or more of five magnets whose circuits are prepared in succession by the sequence relays at the receiving-station. Synchronism is thus established, without the use of distributors, by identity at the two stations of the time interval between the operation of the master relay and each of the set of sequence relays. The five magnets have each one or more armatures, which select the circuit of the desired printing-magnet. Fig. 1 shows the key-board apparatus, and Figs. 4 and 5 the circuits at a combined transmitting and receiving station. Transmitting. Referring to Fig. 1, each keylever 1 is pivoted on a pin 2 and has a series of teeth and notches 3 - - 7 corresponding to the character. When a key is depressed the teeth 3, 5, 7 raise parallel bars 8, 10, 12 and leave bars 9, 11 at rest. Each bar is connected by cranked arms pivoted on the pin 2 to a corresponding switch bar 18 - - 22 co-operating with fixed contacts 23 - - 27. All the key-levers have an end notch 33 which when the key is fully depressed raises a bar 28 and with it a bar 31 into engagement with a contact 32. Referring to Fig. 4, the depression of a key closes the switch 31, opens some of the switches 18-22 and leaves others ,closed. The switch 31 sends an initial impulse to line 36 from the battery 77a, and also energizes the coil 35 of the master relay and swings its armature 39 on to a contact 42. This connects the coil 48 of the first sequence relay across the battery 77<b>, and its armature opens the circuit of the master relay 35 at contact 63, and closes the contacts 68, 74 to energize the second sequence relay 49 from the battery 76. The five sequence relays 48-52 are thus energized in turn and are kept energized so long as contacts 68, 74 are closed, these contacts being maintained by a hold-on coil 73. As each sequence relay is energized, it connects the earthed battery 77a to line 36 through the back contact of the next relay, and thus sends a timed impulse to line through those switches 18-22 that have been left closed by the operation of the key. When the kev is released, a switch 75 across the hold-on coil 73 is closed and all the sequence relays are deenergized. Receiving. When the apparatus is receiving, impulses are sent out from an identical transmitting apparatus at the other end of the line 36. The initial received impulse passes direct to earth through the master relay coil 35 and sets the sequence relays 48-53 consecutively into action as described above for transmission, the time intervals being identical with those at the transmitter. The subsequent impulses, corresponding to the character transmitted, pass through the coil 35 (which restores itself after each impulse) and complete a circuit from battery 77b, contact 42, lead 83, one or other of the five magnets 78-82, and corresponding contact 64-67 of the sequence relays. A selected combination of the magnets 78-82 is thus energized. They are maintained energized, until the completion of the set, by coils 78<a>-82<a> which are not strong enough themselves to attract the armatures. On the energization of the last sequence relay 52, a circuit is made for the battery 77a through the leads 85, 86 connected to the printing-apparatus (Fig. 5). A separate printing-magnet 84 is used for each character and selection is obtained by a multiple branching of the circuit 85, 86 under the control of multiple armatures of the magnets 78-82. As shown in the diagram, magnets 78, 81 have each one armature 87, 108; magnets 79, 82 have each two armatures 90, 91, 111, 112; and magnet 80 has four armatures 96-99. The selective operation of the first three magnets 78, 79, 80 connects the lead 85 to one of the eight sets of four printing-magnets 84; whilst the remaining magnets 81, 82 connect the lead 86 to one of the selected set of four. As an alternative arrangement the last two magnets 81, 82 may have eight and sixteen armatures respectively, and the branching of the lead 85 may be continued until thirty-two branches are obtained, one for each printing-magnet 84. The apparatusmay be employed for wireless telegraphy.