Patent GB-652152-A (GB)
Title: Improvements in or relating to telegraph systems
IPC: H04L12/40
Filed: 1946-06-06
Abstract: 652,152. Electric signalling systems. TELETYPE CORPORATION. June 6, 1946, No. 17178. Convention date, June 14, 1945. [Class 40 (i)] [Also in Group XL (b)] An electric signalling system comprises a central or main station connected to a plurality of secondary stations and provided with means for transmitting to the secondary stations signals for rendering the secondary stations effective selectively in any predetermined sequential order which is capable of variations and means at each secondary station responding to its particular signal and conditioning the secondary station for transmission of information to the central station. The system described is for the collection of hourly weather reports from a number of stations on a loop circuit-the main station including a tape transmitter and a perforated tape carrying a fixed preface to the collection of messages at a particular time and being perforated with signals arranged to condition tape transmitters at the secondary stations in predetermined order to transmit appropriate information set up in perforated tape. A message-end signal from a secondary station operates the main transmitter to send automatically the signal selecting the next secondary station to be brought into operation. If a secondary station fails to respond or if its message-end signal is not received at the main station, an auxiliary transmitter sends a fixed signal comprising a " missing " designation followed by the normal message-end " signal which disconnects the secondary station and initiates the operation of the main station apparatus to transmit the signal group to condition the subsequent secondary station. Selector mechanism at main station. Signal impulses determined by the tape (not shown) operate a selector magnet 31, the start impulse releasing a stop arm 25, 26 so that a cam sleeve 17 is driven by a clutch 23 from a shaft driven continuously by a motor 12. Selector levers 35 whose movement is blocked when the armature 27 is in the marking position and which are provided with projections 38 are sequentially associated with recesses 34 in the cam sleeve 17 and move clockwise in response to marking signals. A bail 20 normally supporting selector bars 39 moves downwardly at the beginning of the rotation of the sleeve 17 so that the bars are supported by the levers 35. If a lever 35 has moved into a recess, its subsequent outward movement engages the end of a slidable selector bar 39 which is moved to the left. The leftward movement of a bar 39 rotates an associated bell crank 44 provided with a projection 48 engaging the end of an associated code bar 49 which moves to the left (Fig. 4) when unlatched. The selective movement of the bars 49 allows one of a number of pivoted bars 59 to fall into aligned notches and through its extension 67 to operate an associated lever 91 ... 96 pivoted at 73 and attached to its bar 59 by a spring 69. The operated lever 91 ... 96 is held by a pivoted latch 76 and the bars 59 are returned to their upper position by a bail 63, Fig. 3, operated from a cam 19 on a cam sleeve 10 released by a member 28 under control of cam sleeve 17. The bars 49 are returned to their right-hand positions where they are retained by the projections 48 on the bell-cranks 44 by the operation of a lever 52 engaging notches 55 in the underside of the bars and operated by a lever 56 and a cam 18. An eccentric 21 operated by a cam on the sleeve 10 actuates a bail 84 engaging a projection 83 on the selected lever 91 ... 96 which is moved to the left and through projection 79 operates the contact member 81 to close the associated contacts 82. Towards the end of its leftward movement the operated lever 91 ... 96 is released from the pivoted latch 76 and moves upwards to its normal position. A shift code bar 87, Fig. 4, occupies one or the other of two position in which it is retained by a spring 88 and is moved rightwardly or leftwardly by the engagement respectively of a projection 99 with a surface 97 or a projection 100 with a surface 98, the projections 99, 100 being formed on the bars 59 associated with the shift or " Figures " lever 92 and the unshift or " Letters " bar 95. The "Carriage Return" levers 93, 96 are associated with the lower case and upper case respectively, the lever 93 having an associated projection 102 which is blocked by a projection 101 on the bar 87 in its righthand position and the lever 96 having an associated projection 103 which is obstructed by a projection 104 when the bar 87 is in its left-hand position. Selector mechanism at secondary station. Figs. 5, 6 and 7. The mechanism is generally similar to that at the main station in respect of the operation of levers 191 ... 199 corresponding to levers 91 ... 96 at the main station. Projections 179, Fig. 7, on the levers 191 ... 199 are associated with helically arranged teeth provided by members 202 on a ratchet assembly 181 carrying an arm 211, Fig. 5, which in its final position operates a member 212 to close contacts 213, the member 212 being latched by a member 214. The ratchet 181 is rotated one step by the operation of a lever 191 ... 199 and is normally retained by a pawl 207. During the return movement of a lever 191 ... 199, the projection 179 slides up an associated surface 203 so that a pivoted latch 219 engages under a projection 225 and holds the lever 191 in an inoperative position. The levers 191 ... 199 are arranged to be operated in the correct sequence corresponding to a group of signals comprising the conditioning signals, the designating signal of the secondary station and a final sequence of signals and the ratchet is stepped until the arm 211 closes the contacts 213. If one of the levers 191 ... 199 is operated out of sequence, the associated tooth on the member 202 of the ratchet assembly 181 is not engaged by the tooth 179 and when the retaining pawl 207 is withdrawn for a short period during each rotation of the cam sleeve 115, the ratchet assembly is returned by a spring 204 to its normal position against a stop 205. The operated pivoted latches 219 are also actuated to the position shown in which the operated levers 191 ... 199 drop to their normal position. A pivoted T-shaped member 189, Fig. 6, has one arm 188 engaged in a notch on the underside of an additional code shift bar 187 and its other arms in engagement with projections on the levers 193, 199, corresponding respectively to "Letters" and "Figures," The selective movement of the lever 193 will move the bar 187 downwardly in Fig. 6 and the operation of lever 199 will move the bar in the opposite direction. The lever 192 is controlled by two of the bars 159 which are provided with laterally directed engaging portions 226, 227, and which are responsive to " Carriage Return " (C.R.) and "Figures" so that the lever 192 is actuated by either of these signals and consequently the first two signals of the conditioning code may be either C.R., C.R., or C.R., "Figures." The movement of the bar 187 by the " Figures " signal allows the bar 217 to be operated in response to the C.R. signal. At the end of a message from a secondary station, a signal comprising "Figures," " Carriage Return " and " Letters " is transmitted and the operation of the upper-case carriage-return bar 217 actuates a link 218 to depress the latch 214 so that the ratchet assembly 181 is released and the contacts 213 are opened. Circuit arrangements. The line circuit extends through a switch 244 which is opened initially to ensure that all secondary stations are in the rest condition. Operation of a key 245 energizes a relay 246 which locks up over a contact 255 associated with the lever 94 and operates magnet 261 of the transmitter 235. Universal lever 91, operated by all signals, closes contact 273 and energizes slow release relays 274, 275. The station selection signals are transmitted over the line 233 and at the called station the selecting arrangement 237 closes contact 213 which effects operation of the magnet 262 of the transmitter 238. The penultimate character of the transmitter calling signal is a " space " which operates the lever 94 opening contact 255 and breaking the circuit of relay 246 which opens the circuit of the magnet 261. The "message - termination" signal from the connected secondary station operates the upper-case carriage-return lever 96 closing contact 265 and energizing relay 266 which locks up over contact 247 of relay 246. When signal transmission ceases, relay 275 releases and closes a circuit for the left-hand winding of relay 246 which locks up, breaks the circuit of relay 266, and initiates the transmission of the signal for the next following secondary station. If the called station fails to respond or does not transmit the end-ofmessage signal, relays 274, 275 release in succession and at contact 283 a circuit is completed for the magnet 288 of an auxiliary transmitter 236 having predetermined cam projections on a cam cylinder and sending a fixed message comprising Figures - Carriage Return-Letters which is identical with the message-end signal from a secondary station by which the lever 96 is operated and a circuit prepared for relay 246 which operates when relay 275 subsequently releases and initiates the operation of the transmitter 235 to condition the subsequent secondary station. Specification 433,503, [Group XL], and U.S.A. Specification 2,296,845 also are referred to. The Specification as open to inspection under Sect. 91 includes a modified circuit arrangement which forms the subject-matter of Specification 652,157, [Group XL (b)], and in which the principal additional feature or modification resides in the provision of a relay controllable according to the current in the line and means responsive to the operation of the line relay to condition the central station for the transmission of the sequential signals. This subjectmatter does not appear in the Specification a