Patent GB-386614-A (GB)
Title: Printing telegraph exchange systems
IPC: H04L12/04
Filed: 1931-04-10
Abstract: 386,614. Telegraph exchange systems. INTERNATIONAL COMMUNICATIONS LABORATORIES, Inc., 67, Broad Street, New York, U.S.A. April 10, 1931, No. 10585. Convention date, May 12, 1930. Void [Published under Sect. 91 of the Acts]. [Class 40 (iii).] The invention relates to a manually-operated telegraph exchange system in which cord arrangements are described for effecting connection of a subscriber station to (1) a telegraph instrument at the exchange office for the transmission of a message to be forwarded subsequently as a telegram or as a cablegram; (2) another subscriber of the same exchange; (3) a subscriber of a distant exchange. Additionally the system includes cord and circuit arrangements for the case when a connection between two exchanges is established through an intermediate exchange. The 'line current is reduced when the line is idle, and the supervisory lamps are associated with the cord circuits and lighted only when action is required on the part of the exchange operator. A subscriber may indicate to the exchange operator by lamp signals the type of call required, and additionally may, by a selector switch, predetermine where at the central station his call is to be answered. Monitoring arrangements are described by which the printer at the exchange may be cut in or cut out on the cord circuits, or may be placed in communication with one subscriber to the exclusion of the other. Subscriber station apparatus [Fig. 2 (C.)] During the idle condition of the line a small negative current from a battery at the concentration board D of the exchange flows through a marginal relay 113 and maintains operated a polarized relay 101. The subscriber apparatus is set into operation by the release of relay 101 on the application of positive potential to the line closing at contact 101A the circuit of a relay 128 to A.C. or-D.C. terminals 124, 137 from which the motor 140 is started by the closure of contact 128A. At 128B the line is extended to a printer magnet 118 and to the contacts 119 of the subscriber's transmitter. The subscriber may effect release of his apparatus by moving a switch 141 to close,contact 141B energizing a release relay 131, breaking the circuit of relay 128 which opens the motor circuit and connects the high resistance winding of relay 101 to the line circuit. Connection with exchange printer. A call for an exchange printer is selectively indicated at the board D by the operation of moving the key switch 141 to the calling position and returning it to the normal position. In the calling position the high resistance winding of relay 101 is shunted, and relays 113, 143 operate in succession, but on the return of the key to normal relay 113 releases, and call lamp 155 is illuminated. The operator inserts plug 161 into the jack 115 of the calling subscriber causing the release of relay 143, and battery at the board D energize a relay 162 at the operator's position, which illuminates call lamp 163, sets the printer motor 160 into operation energizes the printer receiving relay, and applies positive potential to the line 102 leading to the calling subscriber where relay 101 releases to set the motor into operation and to increase the line signalling current by the short circuiting of the high resistance winding. Release of exchange printer connection. The exchange operator opens key 171 removing the short circuit around sleeve relay 174 which operates and locks up. Relay 162 releases and disconnects the printing apparatus. At contact 174C, the disconnect lamp 197 is illuminated and at 174B negative potential is applied to the line to operate relay 101, Fig. 2 (C), and to stop the subscriber's motor. When the plug 161 is withdrawn, sleeve relay 174 releases, and the current is restored to normal. The calling subscriber may initiate a further call if the plug 161 has not been removed by operating recall key 120 which operates at the printer station relay 190 and subsequently relay 162 to restart the printing apparatus. Connection other than to an exchange printer. The calling subscriber maintains the key 141 in the closed calling position, energizing relays 113, 143 over the contacts of which calling lamp 148 is lighted. The operator extends the connection by inserting a plug 205 into the calling jack 115, extinguishing lamp 148 and operating sleeve relay 206 which extends the line through a marginal relay 215 lighting call lamps 167, 226. at the junction switchboard. The operator inserts a plug 230, Fig. 3 (H), into jack 210 operating over the winding of relay 251 a relay 240 lighting busy lamps 242, 243 and releasing relay 215 controlling lamps 167, 226. Sleeve relay 251 completes an energizing circuit for the right-hand windings of relays 257, 258 which operate to their -marking contacts. Positive potential is applied over contact 257M and the line winding of relay 258 to the tip of plug 230 and over the line 102 to set the apparatus of the calling subscriber into operation. The exchange operator moves his monitoring key 306 to the position in which the calling line is extended to printer apparatus 318, 578 on which he obtains the name or number of the desired subscriber. On inserting plug 268 into the jack 210 of a switching cord F, Fig. 2, relay 240 operates and lights guard lamp 229. The switchboard operator inserts plug 205 into the jack 256 of his printer and ascertains the number of the called subscriber, and by plugging into the jack 115 effects the operation of relay 206 which at contact 206B short-circuits a resistance which increases the current to operate sleeve relay 259. Positive potential is applied over marking contact 258M and the line winding of relay 257 to release relay 101 at the called subscriber's station where the printing apparatus is started into operation. Message transmission. The signalling circuits for the subscribers extend over the line windings of the respective relays 257, 258 and over the marking contacts 258M, 257M respectively. The two left-hand windings of each of the relays are arranged differentially and a third right-hand winding is arranged to maintain the armatures of the relays on their marking contacts when the circuits of both left-hand windings are open. When the line winding is without current, the second left-hand winding moves the associated armature to its spacing contact. With a signalling interruption from the subscriber connected to the plug 268, current passes over:the second winding of relay 257 to move its armature to its spacing contact, thus opening the circuit from a battery 291 over the line winding of relay 258 to the tip of the plug 230 connected to the second subscriber and also of the second winding of the relay 258 so that its armature is still maintained against its marking contact by the right-hand winding. By operating a split key 315, Fig. 4, the operator at the junction switchboard can enter into telegraphic communication with either of the connected subscribers to the exclusion of the other. If the disconnected subscriber wishes to recall the operator he opens his recall key 120, Fig. 2, releasing a relay 342, Fig. 5, operating a slow relay 348 which lights a recall lamp 355. Release of subscriber connection. If either subscriber operates his key switch 141 to the position cutting out his motor, one of the corresponding relays 257, 258 is released, but the other relay remains energized through its right-hand winding. Assuming that relay 257 is released slow-relay 362, which is not operated by the signal transmission, pulls up, lights lamp 384, and operate relay 298 which cuts the interconnection between the relays 257, 258. Assuming that 'the subscriber connected to plug 230 and relay 258 now releases, relay 363 operates, and lights lamp 378 when the operator removes the plugs 230, 268 lighting guard lamps 229 at the switchboard. Plugs 205 are then taken down, releasing sleeve relays 251, 259 which open the circuits of relays 362, 363 extinguishing the lamps 378, 384 and restoring the circuit to normal. Either' subscriber may recall the central station operator by opening and closing the key 120 through which relay 362 or -363 is periodically energized to flash lamp 384 or 378. Connection of subscriber line to junction line leading to a distant exchange. The operator inserts plug 231 into a jack 210, operating relay 451 to light lamp 459, and since relay 206, Fig. 2, has already been operated marginal relay 234 pulls up and connects positive potential from battery 437 to the subscriber's line. Relay 449 operates and later relay 463 pulls up to extinguish supervisory lamp 459. By moving monitoring key 312 the operator obtains on his printer set 318, 578 the name of the desired exchange. When plug 412 is inserted into a jack 387 of an idle junction line, relay 385 operates and sends over the line 407 a marking impulse which operates relay 406 at the distant exchange, where relay 417 is operated and lights call lamps 418, 419. When the distant exchange answers by inserting a plug 412 into a jack 387, relays 481, 487 operate and -effect the operation of relay 385 which sends a marking impulse operating relay 406 at the home exchange. Relays 481, 487 pull up, extinguishing lamp 477 and. extending the line through monitoring key 312 to the calling operator who communicates the desired number to the distant exchange;-where a plug 231 is inserted into an idle switching jack 210. The relay 234 of the distant exchange is operated when a plug 205 is inserted into the jack 115 of the called subscriber, and extends the line to the called subscriber with the application of positive potential to the relay 101. Message transmission. The terminal arrangements of the junction line 407 provide for duplex working, outgoing signals being transmitted from the contacts of relay 385, and received signals operating relay 406 from whose armature they are applied over two differential windings of a repeating rela