Patent GB-555375-A (GB)
Title: Starting sequence system for telegraphs
IPC: H04L12/12
Filed: 1942-05-22
Abstract: 555,375. Starting sequence systems for telegraphs. TELETYPE CORPORATION, and ZENNER, R. E. May 22, 1942, No. 7003. [Class 40 (iii)] A telegraph transmitter controlled by a tape on which are recorded characters to be transmitted, for example in facsimile fashion, comprises means to suspend the operation of the transmitting mechanism, starting means adapted to be brought into engagement with the continuously running driving motor so as to be moved thereby to an operated position, and means to cause the starting means during its movement first to transmit one or more impulses to start the driving motor of the receiver and afterwards to release the transmitting mechanism. Transmitter.-Figs. 1 and 2. The characters to be transmitted are represented by pairs of cam discs 13 on a shaft 9, one cam disc for a lower case character and the other for the upper case character. Each pair of cam discs co-operates with a pair of brushes 65, 66 to produce signal equivalents of the scanning of characters in vertical lines. The brushes are carried by a brush support 63 pivoted on a rod 64 and formed with a lug 67 lying over a corresponding selectable bar 61 co-operating with notches in permutation bars 31 ... 35. These bars are set by the release of catches 44 by electromagnets 37 ... 41 controlled by contacts 54 of a corresponding number of sensing levers 47 co-operating with a punched tape 48. The code used in this sensing arrangement is a fiveunit code and provides also for production of case shift signals which control the position of bars 90, 91 by the permutation bars 31 ... 35 and thereby through linkwork 89, 88, 87 the position of a switch arm 86 against a contact 84 or a contact 85. These contacts are connected to brushes 82, 83 co-operating with insulated collecting discs 15, 16 connected by rods 17, 18 to the cam discs of each pair corresponding respectively to lower and upper case characters. The shaft 9 which carries the cam discs 13 is continuously driven and also carries cams such as 24 ... 27 for timing the various operations of the transmitter. The cam 24 operates on a lever 76 to depress the selectable bars 61 by means of a bail 80 until the permutation bars 31 ... 35 have been set, when the cam 24 allows the bail to rise thereby permitting the selected bar 61 to rise and turn its corresponding brush support 63 into operative contact with its cam discs. The brush support thus selected is then locked by a bail 70 controlled by the cams 25, 26, so that the sensing of the next signal code and the operation of the secting device accordingly can proceed while the signal is being sent by the selected cam disc. The cam 27 serves to close contacts 116 as mentioned below. In a slightly modified transmitter, Fig. 5 (not shown), the magnet 51 is omitted and a few other consequential changes are made in the circuits. Starting and stopping devices.-The transmitter is provided with relays 117, 118 controlled by an arm 107 adapted to be driven by or released from screw 30 on the continuously driven shaft 9 under the control of a magnet 103 controlled by switches 99, 96. The switch 99 is intended to be closed by hand when transmission is desired. The switch 96 is normally closed, but will be opened by a bell-crank lever 93 if a loop in the tape 48 is taken up by stoppage of device feeding the tape to the sensing fingers 47. When either switch 96 or 99 is open or when both are open, the magnet 103 is switched off, and the arm 107 is at the right end of its stroke and away from the screw 30. The relay 118 is then cut off from the contacts 116 by the open contacts 114, but the relay 117 is in circuit with the contacts 116 and when these contacts are closed by the continuously rotating shaft 9, the relay 117 is energized, closing contacts 117a. This closes a circuit through contacts 118a, 117a, thereby energizing holding-on coil 1176 and in series therewith the magnet 57 which puts the tape sensing devices out of action. When the switches 96, 99 are both closed, the magnet 103 is switched on, the arm 107 which is pivoted to the armature 104 of the magnet is drawn against the screw 30, a tooth 109 on the arm engages the screw, and the arm is driven to the left by the screw. During this movement the arm causes the temporary closing of two contacts 112, 113 in succession, each causing an impulse to be sent out by a signal transmitter 78 to a signal receiver 79 of a receiving apparatus 81, the motor of which is thereby set in operation as described below. After this, when the arm 107 reaches the end of the screw 30, it closes contact 114. Then, when contacts 116 are next closed by cam 27 of shaft 9, the relay coils 117, 118 are both energized, contacts 117a are closed, but contacts 118a open and the holding- on coil 117b and the electromagnet 57 are deenergized, so that the tape sensing operation can proceed under control of the electromagnet 50 by the contacts 116. The signals are then transmitted. If the switch 99 or 96 is opened, the parts are returned to the rest position and transmission ceases. Receiving apparatus, Fig. 4.-This receiver, which is generally of the kind described in Specification 380,217, comprises a printing wheel 126 co-operating with a platen 125. The printing wheel 126 is driven through gearing 135, 134 by a motor 127, and motion is transmitted from the shaft 136 of the printing wheel through worm gear 138, 139, shaft 140, and worm gear 141, 142 to a screw 144 with which a tooth 145 on an arm 147 is engageable. The arm 147 is pivoted to the armature 148 of a magnet 149, and serves to control the switch 152 of the motor 127. The magnet 149 is in series with a reactance coil 157 and contacts 156, 155. The contact 156 is carried by the insulated end 119 of the armature 131, which carries the printing platen 125 and is pivoted at 158 for operation by the electromagnetic unit 124 comprising two coils 129, 130 controlled by a polarized relay 100 operated by the received signals. In the rest position, contact 122 is closed, coil 130 is energized, contacts 156, 155 are closed, magnet 149 is energized, arm 147 is in engagement with screw 144 and holds switch 152 open, all as shown, so that the motor 127 is at rest. When the starting signals produced at the transmitter by the successive closing of the contacts 112, 113 are received by the polarized relay 100, contact 122 is broken and contact 123 closed. This energizes coil 129 instead of coil 130, thereby opening contacts 156, 155 and de-energizing magnet 149. Springs 151, 150 then lift arm 147 from screw 144 and move it away from switch 152, which closes and starts the motor 127 before the transmission system is made operative by the closing of contact 114 at the transmitter. During reception, contact 122 is temporarily made and broken. The closing of this contact energizes the magnet 149, which urges arm 147 against screw 144 ; but the duration of the contact is not long enough to cause the arm to reach the switch 152. When, however, the transmission ceases, the arm 147 is engaged and driven by the screw until it reaches and opens the switch 152, thereby stopping the motor 127.