Patent GB-476273-A (GB)
Title: Improvements in or relating to communication systems
IPC: H04L25/49
Filed: 1936-12-01
Abstract: 476,273. Type - printing telegraphy., INTERNATIONAL BUSINESS MACHINES CORPORATION. Dec. 1, 1936, No. 32936. Convention date, Dec. 14, 1935. [Class 40 (iii)] In a type-printing telegraph system using synchronous distributers at the transmitter and receiver, character selection is effected by impulses of the same number and polarity for each character, but differentiated in respect of time. As described, a character signal comprises two impulses, the first of which selects a group of characters whereas the second selects a character within this group. The impulses which may be transmitted by line or wireless are received on the grids of gas-discharge tubes controlling relays in their anode circuits. Keyboard transmitter, Fig. 1. Individual contacts 33 controlled by the keys are arranged in groups of 7 and each contact operates a corresponding group relay 35 (8-14) and a relay 35 (1-7) according to the position of the contact in the group. The two relays operate in series, connect the corresponding distributer segments 1-7 and 10-14 to line and lock up in series with 49 which operates 54 to open the original circuits of relays 35. The distributer brush 60 is connected to line when segment 16 and a corresponding segment in ring 61 engage their brushes 60, 62 which short circuit the negative bias battery of gasdischarge tube 71. Relay 70 in the anode circuit pulls up and connects brush 60 to line over ring 57 and brush 58, the locking circuit of relays 35 being maintained over ring 64. Two timed impulses over 59 (1 to 7 and 8 to 14) follow whereupon insulating segment on ring 64 releases the relays 35, 49 and 54, and is followed by insulating segment 83 on ring 63 which opens the anode circuit of valve 71 to release relay 70. A synchronizing signal is sent over segment 15 and the corresponding segment of ring 61 if switch 85 is closed. Receiver. Fig. 2. The distributer ring 96 has segments 1-7 and 8 ... 14 connected in pairs to the grids of discharge tubes 112 (1-7) the plates of which are connected over the windings of relays 114 (1-7) and 115 (1-7) in parallel pairs, the other ends of the windings being connected to individual brushes 116 (1-14) which, over distributer segments 118 and brushes 117 complete the anode circuits at the required times. The first of the pair of incoming impulses over segments 1-7 trips a tube 112 (1-7) and operates a relay 114 (1-7) which locks up and prepares a circuit for a horizontal row of the printing magnets shown at the right of the Figure. The conducting segments 119 over which the plate circuits are completed are long enough to permit locking of the relays, the energized tube then releasing. Similarly the second impulse over segments 8 ... 14 operates a relay 115 (1-7) which locks and prepares a circuit for a vertical row of printing magnets. Subsequently when distributer brush 154 passes conducting segment 150, an operating circuit is completed for the printing magnet at the intersection of the selected horizontal and vertical rows. Distributer brush 136 then runs off its conducting segment and the two selecting relays are released. Synchronizing. If the receiving distributer is lagging or leading, the synchronizing signal from the transmitter comes in on segment 21 or 22 and causes one or other of discharge tubes 102 to strike and operate magnet 103 or 104 to correct the distributer as described in Specification 442,596. Relay 107 or 108 pulls up slowly to restore the discharge tube. To bring the receiver into synchronism when the distributers are started up, switch 106 is thrown to connect the long segments 23, 24 to the discharge tubes one or other of which then acts intermittently on the correcting mechanism. Switch 105 is also opened at this time to prevent operation of the receiving tubes.