Patent GB-348110-A (GB)
Title: Improvements in or relating to selective control arrangements for printing telegraph systems
IPC: H04L12/40
Filed: 1930-02-05
Abstract: 348,110. Telegraph party-line systems. STANDARD TELEPHONES & CABLES, Ltd., Columbia House, Aldwych, London.-(Western Electric Co., Inc. ; 195, Broadway, New York, U.S.A.) Feb. 5, 1930, No. 3888. [Class 40 (iii).] In a party-line system of printing-telegraph stations connected in series, with current flowing in the line during idle periods, any station can select a station or group of stations, or issue an omnibus call, by starting the printer-motors at the selected stations, the motors at the non-selected stations remaining idle. The system may comprise branches connected to the main line through relays, Fig. 1 (not shown). A single pulse (such as one due to a lightning surge) fails to effect any connection. "Busy" and " idle " indicator lamps may be provided. Selection of called stations. Fig. 2 (not shown), illustrates a system allowing of calls comprising from 2 to 10 impulses (interruptions), the 10 (or " zero ") call effecting an omnibus connection. In a modification, Fig. 3, the calls comprise from 2 to 9 interruptions preceded or not by a zero group of 10 interruptions, so that 17 stations or groups of stations can be accommodated. Dialling comprises interruptions of the contacts s at the calling station. At the called station the armature 1, which is normally on the right-hand or marking contact M, is moved to the left by a biasing winding at each interruption of the line-current. The armature 1 completes a circuit for the stepping-magnet 14 and slow-release pause-magnet 15 via the contact BÀ1 of the 3-banked rotary switch 20, for the first impulse and via the armature 15Àa for subsequent impulses. For single-digit calls the wipers stop on one of the earlier contacts which, for the called station, is connected in the case of bank C to the lead 101 so that when the pause magnet 15 releases at the end of the call, a circuit is closed for the printer-control magnet 13 via 101, CÀ24, 15Àc, 33, AÀ31, the printer-motor 11 being thus started up. For a two-digit call, the first digit is zero and takes the switches to the eleventh point. The first impulse in the second digit energizes magnets 14, 15, via point BÀ11, and the subsequent action is as before. False actuation by single impulse. In response to a single impulse due to a lightning surge, the switch 20, Fig. 3, is stepped round to zero under the control of magnet 16, since magnet 15 releases while the switch is at point AÀ2. Magnet 16 consequently pulls up, holds on via 16Àb, and cuts in the stepping magnet 14 via 16Àa and the self-interrupting contact 25, this circuit being maintained till wiper AÀ24 has been stepped off the segment AÀ32. The wipers are carried over the eleventh point during the stepping-home process by the connection of point AÀ11 to the lead 33. Omnibus call. At every station the point CÀ21, Fig. 3, is connected to lead 101, so that a OO call effects an omnibus connection. Transmission of message. Message impulses pass through the receiver 2 and idle transmitter 3, and do not disturb the connection, since the left-hand contact S is cut off at bank B from the selectors at all stations. Clearing. Clearing is effected by a prolonged interruption of the line at the key 7 of the calling station. The prolonged breaking of contact at M enables the condenser 10 to become charged. On restoration of the key 7 it discharges through the righthand winding of relay 16, which holds on and effects stepping-home of all rotary switches 20, as described above, and breaks the holdon circuits of motorcontrol relays 13, 17. At the calling station the condenser 10 charges more slowly than at the called stations, owing to the cutting-in of resistance 9 ; thus the stopping of the motor at the calling station indicates that the interruption has been long enough to clear all stations. Motor-starting at calling station. At the calling station the of-normal contacts 6 are closed during dialling, so that the magnet 17 is energized via segments AÀ31, AÀ32, or AÀ11 and 17Àa, as soon as the local selector switch has been stepped off the first two points. Motor-control relay 13 is thus cut in at 17Àb, but it fails to act until the cessation of dialling removes the short-circuit at 6. Thus the call-up impulses do not actuate the pointer at the calling station, since its motor does not start until dialling has ceased. Modification accommodating 80 stations or fixed groups of stations. The arrangement shown in Fig 4 provides for 2-digit calls, and the first digit is not restricted to a zero value. The arrangements for clearing after a call and after a single impulse are similar to those shown in Fig. 2, except that an additional relay 37 and two contacts 16Àc are required for stepping the switches home. When a call is made, the first digit steps the switches, in the manner described above, as far as a C contact which, at the called station only, is connected by lead a<1> to a hold-on magnet 34. This magnet closes at 34Àa one gap in the circuit from battery 19 through motor-control magnet 13. After the magnet 34 has locked up, the slow-operating magnet 37 pulls up, and cuts in at 37Àb the switch-stepping circuit through stepping magnet 14 and selfinterrupting contacts 25. The selector switches at all stations are thus stepped to position 12, where earth at 21 is cut off from magnet 37 and stepping ceases. At the non-called stations the magnets 34 did not pull up, since their circuits were broken at 15Àa by the pause magnet 15 until dialling ceased. The second digit steps the rotary switches to the point where, at the selected station, the second gap in the circuit of motor-control magnet 13 is closed via lead b<1> by wiper CÀ24, so that motor 11 starts up, each digit having closed one of the gaps at 34Àa, C. At the calling station the switch is stepped as far as position 12 by the first digit, as in the case of the other stations, but it stays in that position for the remainder of the action, since the off-normal contact 6Àa of the dial-switch cuts in the self-locking relay 35 via CÀ12, and the stepping magnet 14 is thereafter cut off at 35Àa. The motorcontrol magnet 13 is thus energized at the calling station via contacts 35Àb, but not till contact 6Àb closes at the end of the dialling. An omnibus call comprises one group of 10 interruptions and cuts in at CÀ11 the magnets 35 at all stations, the motorcontrol magnet 13 being thus cut in via 35Àc. Magnet 35 holds on via 35Àb, but the switches are stepped on to point 12 by the action of magnets 37, 14, as soon as magnet 15 releases at the end of the call. Message signals still operate armature 1 but do not disturb the connection, since magnets 15, 14 are now cut off at 35Àa. Modification for selecting an arbitrary number of stations. In a modification, Fig. 5 (not shown), a number of stations may be called in succession. The motors at all the called stations are then started by a final group of 2 impulses, the numbers 1 and 2 being not used as the first digit of any call. The first digit energizes at the called station a self-locking magnet 40, Fig. 5 (not shown), which is connected to the point in bank C which corresponds to that digit. This magnet prepares for a further self-locking magnet 17, Fig. 5 (not shown), a circuit which is completed by the second digit through the wiper of bank C in its second-digit position. Segments 34, 35 being joined together in this Figure, the slow-operating magnet 37 then effects stepping-home of all switches, leaving one the gaps in the circuit of motor-control relay 13 closed by the armature of magnet 17, Fig. 5 (not shown). This magnet holds on until cut off by the clearing signal, which effects energization of magnet 16, Fig. 5 (not shown). Thus further calls may be given and magnets 17 at further stations may be locked up, before the second gap in the circuit of each selected control relay 13 is closed through point 3 of bank C, Fig. 5 (not shown), on the dialling of a third group of two impulses. The switches of all stations remain at point 3 till the clearing signal causes them to be stepped home. The magnet 17 which prepares the circuit of the motor-control magnet 13 in Fig. 5 (not shown) is operated also at the calling station by the off-normal contact 6b of the dial switch, so that the motor at the calling station starts with the others. The point in bank C corresponding to zero of the second digit is in this modification multipled to the off-normal dial contact, so that an omnibus call can be effected by the emission of any call ending in " 02." Modification employing 2-bank selector switches : response of called station. In the arrangement shown in Fig. 6 the selector switches step home after registering the call on hold-on relays. Twodigit calls followed by an executive signal (zero) are employed, the call of the station illustrated being 85 ; the digits must be different, and 42 distinct calls are available. The first digit, comprising in the example 8 interruptions of line L, moves the earthed armature 69 of line relay 65 to the right eight times and so operates the stepping magnet 61 which moves wiper 58 to its eighth contact and so prepares a circuit for the registering- magnet 76 of the first digit. This magnet is cut off at 71Àa, however, until the slow-release pausemagnet 71, having been kept energized by the impulse train, releases at the first pause. The switch-release magnet 62 is temporarily cut off at 73Àa by a slow-acting magnet 73 which was cut in via 71Àb as soon as the off-normal contacts 72Àa were closed by the displacement of the selector switch. At the first pause the pause magnet 71 cuts off at 71Àb the slow magnet 73, but before the latter releases the registering magnet 76 at the selected station pulls up (via 72Àa, 71Àa, 73Àe, 70Àf, 58, 76, 77Àb, 78Àa) and locks itself via 76Àb independently of the wiper 58 and contact 73Àe. When the slow magnet 73 releases, switch-release magnet 62 is cut in at 73Àa and release