Patent GB-151748-A (GB)
Title: Operating synchronous telegraph systems
IPC: H04L25/49
Filed: 1919-07-07
Abstract: 151,748. Benjamin, G. R. July 7, 1919. Type-printing telegraphs.-In a type-printing telegraph system of the kind in which combinations of positive and negative impulses are sent to line by means of a perforated-strip transmitter, means are provided for suppressing successive current impulses of like polarity, thereby reducing the static charge on the line. The contact members of the strip transmitter are provided with locking-devices each of which holds a member in its inoperative position after sending a current impulse of one polarity until a current impulse of opposite polarity is sent by the other member. Transmitter. A motor 2, Fig. 1, oscillates a bar 18 through gearing 5, 6, an eccentric 7 and a lever 8 upon which the bar 18 is mounted. The bar 18 rests upon the arms 12 and 14 of two spring-controlled, bellcrank levers pivoted on a bar 15 and carrying contacts 26 and 27 respectively. The arms 12 and 14 are adapted to be engaged by latches 31 and 32 which, when drawn against fixed stops by springs 31<1>, 32<1> engage the arms 12 and 14. The latches 31 and 32 are moved to inoperative positions by means of magnets 34 and 35 the circuits of which are controlled by a polarized relay 50. The winding 46 of the relay 50 is energized in series with the winding 41 of a sending relay SR by a battery 40 when the contacts 27, 29 are closed; while the winding 47 of the relay 50 is energized in series with the winding 42 of the relay SR when the contacts 26, 28 are closed. The upward movements of the arms 12 and 14 under the actions of their springs 16 and 17 are controlled by rods 20 and 21 engaging a perforated strip 23. Receiver. The cable relay CR controls the windings 61, 62 of a polarized relay LR the tongue of which connects a battery 65 to the arm 67 of a rotary distributor D, operating in synchronism with the strip perforated transmitter of the transmitting station, when positive impulses are received by the relay CR. The contact segments 1, 2 - - 5 of the distributor D are connected to the operating windings of selecting relays r<1>, r<2> - - r<5> in order that these relays may be energized when positive impulses are received by the relay CR. At the end of each revolution a contact on the arm 67 closes the circuit of a clear-out relay CR<1> thereby breaking the circuit of the holding windings of the relays r', r2 - - r<5>. Operation. In transmitting a character the signal impulses of which are two positive followed by three negative impulses the strip 28, Figs. 1 and 2, is punched as shown under the letter A, Fig. 2, so that when passed through transmitter the rod 20, Fig. 1, passes through the first perforation while the upward movement of the rod 21 is checked by the tape. Under this condition the contacts 26, 28 close the circuit of the magnet 42 of the relay SR and the winding 47 of the relay 50. The operation of the relay SR sends a positive impulse to line C from the battery 52. The energization of the relay CR at the receiving station by a positive impulse causes the tongue of this relay to energize the winding 61 of the polarized relay LR from the battery 60, thereby. connecting the rotary arm 67 of the distributor D to the battery 65. The simultaneous engagement of the arm 67 with segment 1 of the distributor causes the energization of the selecting relay r' which locks up over its front contact. The energization of the winding 47 of the relay 50 causes the tongue 56 of this relay to occupy the position shown, thereby withdrawing the latch 32 from engagement with the arm 14 and allowing the latch 31 to engage the arm 12, so that upon the next downward movement of the arms 12 and 14 the arm 12 is held in its depressed position, while the arm 14 may rise with the rod 18. Under these conditions no impulse is sent to line C after the strip 23 has been fed one step since the movement of the free rod 21 is arrested by the unperforated strip. Since, however, the relay LR has not been operated, the selecting relay r<2> will be energized when the distributor arm 67 engages segment 2. A further movement of the strip 23 causes a perforation to appear over the rod 21 so that when the latter rises the contacts 27 and 29 engage to energize the magnet 41 of the relay SR and the winding 46 of the relay 50. The operation of the relay SR sends a negative impulse to line C from the battery 52. The energization of the relay CR at the receiving station by a negative impulse causes the tongue of this relay to energize the winding 62 of the relay LR, thereby disconnecting the rotary arm 67 of the distributor D from the battery 65. The simultaneous engagement of the arm 67 with segment 3 of the distributor causes no energization of the selecting relay r<3>. The energization of the winding 46 of the relay 50 causes the tongue 56 of this relay to energize the magnet 34 thereby disengaging the latch 31 from the arm 12, while the magnet 35 is de-energized to allow the latch 31 to engage the arm 14 so that when the next two perforations appear over the rod 21 in succession no impulses are sent to line and the selecting relays r<4> and r' are not energized.