Patent GB-517308-A (GB)
Title: Improvements in or relating to telegraph apparatus
IPC: H04L17/30
Filed: 1938-07-19
Abstract: 517,308. Printing telegraphy. STANDARD TELEPHONES & CABLES, Ltd., and HYDE, G. A. M. July 19, 1938, No. 12582/39. Divided out of 517,297. [Class 40 (iii)] In a telegraph system using impulse-combinations, the transmitter and receiver are each connected to a common set of contacts on the distributor for use in both transmission and reception. The receiver is started into operation by a spacing signal followed by a marking signal, and when the spacing element is received by the line relay LR, relay MS operates and locks up over its contact ms1. The marking element applied over contact ms2 operates relay CS which at contact cs1 operates relay ST which locks up over its contact st2. When the start (spacing) impulse is received clutch magnet CM is energized and the distributor is connected to the motor shaft for one revolution. After the distributor has passed from contact with brush RSB, the clutch magnet is de-energized, the back contact cm2 (Fig. 2) being closed but contacts cm3 (Fig. 2) and cm4 (Fig. 1) are kept in operated condition by a cam on the distributor shaft as long as the distributor is out of its normal position. The contact cm1 is kept open sufficiently long to allow the relay ST to release and to break the circuit of the relay CS. The code impulses received by the relay LR are repeated by contact lr1 and brushes M1 ... M5 to charge condensers QA ... QE. When the segment 11 reaches the brush SB, the stop (marking) impulse operates relay ST which locks up over contact st2. At contact st1 the magnet CM is reconnected to the start brush RSB and at contact st4 the relay STA is energized. At contacts sta1 ... sta5 the condensers are connected to relays A ... E and when contacts cm2, cm3 close the printing relay PR operates and locks up over contact pr1. The storage relays cause the rotation of the type wheel to the desired position as described in Specification 517297. When the telegraph apparatus is used for transmission, the switch SRS is moved to the position S. With the relays MS, CS and ST operated, the actuation of a key closes a circuit for a relay SR which at contact sr1 energizes the magnet CM to start the distributor into rotation. The condensers QA ... QE are charged according to the code combination of the key depressed and connect positive or negative battery to the brushes M1 ... M5 which operate relay LR and cause the corresponding marking and spacing impulses to be sent to the line at the contact lr1. At contacts sr2, sr3 the start and stop impulses. are sent to the line over brushes SSB, SB. The circuit of the magnet CM is broken by the release of relay SR and when distributor segment 11 passes the brush RSB, relay SS is energized in series with the relay LR and at contact ss3 breaks the circuit of relay SR and at ss4 opens the circuit of relay PR. At contacts ss5 a circuit is completed for relay STA which locks up and connects the condensers QA ... QE to the storage relays A ... E. The motor may be stopped from a distant station by sending the start signal, five spacing signals and the stop signal with the result that earth is connected to the lead 13 thereby short circuiting the relay M5.. Fig. 3 shows an answerback device incorporated in the arrangement. When the " who are you signal has been received the type-wheel connects ground to relay AB which locks up and at contact ab10 completes a circuit for relay SR which operates clutch magnet CM and the first combination of marking and spacing impulses is applied over contacts ab1 . . . ab5 to the distributor. When the distributor has completed its revolution relay SS operates and breaks the circuit of relay SR. The magnet DM is energized and steps the brushes on to the set of contacts corresponding to the next character of the answer-back signal. When all the characters of the return signal have been transmitted relay ABR is operated in series with the magnet DM and at contact abr1 opens the circuit of relay AB which at contact abr2 prevents relay SR from further operation. The magnet DM is energized over its interrupter springs until the answer-back wiper switch reaches its first bank of contacts and then de-energizes.