Patent GB-1198401-A (GB)
Title: Transmission Device for a Start-Stop Teleprinter
IPC: H04L12/06
Filed: 1968-03-19
Abstract: 1,198,401. Telegraphy. ING. C. OLIVETTI & C. S.p.A. 19 March, 1968 [24 March, 1967], No. 13250/68. Heading H4P. A start-stop teleprinter includes a set of cross-shaped transfer members 12, Fig. 2, each of which is selectively placed in one or other of two positions for transferring the corresponding bit of a code signal to a transmission bar 8 which is sensed by a mechanical distributer described in Specification 1,159,835. Transmission from keyboard.-When a key is depressed the bars of a set of code bars are selectively positioned to represent the corresponding code combination and act on slides 19 via a store described in Specification 1,178,569. Cam 30 now rotates and moves bail 27 anticlockwise about shaft 28, rotating lever 25 about stud 36 so that frame 22 is raised, lifting each slide 19 upwards. Consequently one or other shoulder 17, 18 engages a corresponding arm of each cross-shaped transfer lever, rocking it to left or right and so setting up the transmission bars 8. As the frame 22 rises lug 59 unlatches bail 55 from lever 50 so stopping clutch 43 after one revolution. Answer - back transmission.- A mechanical drum store 60, Fig. 3, has a number of axial slots each mounting a toothed strip 63 which represents one code combination. When the Here Is key is depressed slide 120 is moved leftwards and arm 138 moves anti-clockwise to lock slide 120 in this position. Via spring 121 slide 120 moves slide 111 leftwards so that bail 106 is moved anticlockwise and releases clutch 43. Lug 105 of bail 106 moves bail 99 and latch 37 anticlockwise, so releasing stud 36, Fig. 2. This prevents frame 22 from being raised and so no character from the keyboard can be transmitted during transmission of the answer-back message. The movement of bail 99, Fig. 3, also causes stud 97 to be latched. When now cam 30 rotates bail 27 rotates arm 94 clockwise about stud 97, raising shaft 92. Shaft 92, Fig. 5, carries with it a frame on which are resiliently mounted sensing levers 66 which are selectively positioned by the toothed strips on the drum 60. Depending onwhether or not a tooth is present projection 80 or 79 on each sensing lever 66 engages a corresponding arm of the cross-shaped transfer lever 12, thereby selectively positioning transmission bars 8. The subsequent lowering of the sensing lever frame causes the drum to be stepped once. The sensing cycle is repeated until the drum has made a complete revolution whereupon tooth 140, Fig. 3, moves lever 138 clockwise, releasing slides 120 and 111 which move rightwards. Consequently bail 106 moves clockwise and the clutch is disengaged. If the Here Is key is operated while the teleprinter is transmitting, slide 111 is prevented from movement by engagement of lug 122 with tooth 113. When transmission ceases the tooth is released and slide 111 is pulled leftwards by spring 121 so that transmission of the Here Is message now takes place as already described. Slide 120 is also moved by lever 130 in response to a Who Are You signal, with resultant transmission of the Here Is signal. Transmission from tape.-Bars 200, Fig. 2, are selectively positioned in accordance with the character read from the tape as described in Specification 1,174,317. These bars are coupled to the transmission bars 8 by way of shafts 202. When the start key 176, Fig. 7, is depressed lug 267 releases latch 162 which couples teleprinter shaft 31 to the tape reader shaft 160. Also, slide 193 moves rightwards, unless prevented by lug 199 because the teleprinter is already transmitting. Consequently bail 106 moves anticlockwise, engaging the clutch as already described, and, via link 194, bail 99 is moved axially rightwards so preventing engagement of latch 98 and stud 97, Fig. 3. Bail 106 also rocks bail 99 clockwise so that latch 37 cannot engage stud 36, Fig. 2. Hence neither the keyboard nor the answer-back drum can transmit during transmission from the keyboard. Operation of the stop key 187 causes resetting of the various parts and cessation of transmission. If the start key is operated when the teleprinter is transmitting spring 172 is tensioned so that when lug 199 releases slide 193 at the end of transmission lug 267 releases latch 162 and slide 193 moves, as described above.