Patent GB-803728-A (GB)
Title: Telautograph system
IPC: G08C21/00
Filed: 1957-01-25
Abstract: 803,728. Writing telegraphs. CREED & CO., Ltd. Jan. 25, 1957 [Jan. 26, 1956], No. 2782/57. Class 40 1). In a writing telegraph system the transmitter pen is joined by a pantograph to variable resistors which modulate alternate half-cycles of an A.C. supply and thereby control the receiver pen correspondingly. The half-cycles are passed via rectifiers 25, 26 to resistors 15, 16, which are controlled by movements of the pen 12. The lines L1, L2 are normally joined to the recorder but when switch 19 is made and the calling button 52 is depressed relay 18 is energized from the transformer 22 via line 36, A contacts of the paper feed switch 37 and the platen switch 39, the earth return being via the A contacts of the local recorder relay 49 and of the calling button 52. Relay 18 then connects lines L1, L2 to the transformer 23 via the rectifiers and resistors 15, 16, and at the same time supplies D.C. via line 43, paper feed camswitch 44, leads 45 and 46 and resistor 48 to line L1. The return path is via lead 56 and resistor 53 at the distant recorder (not shown but numbered the same as the local recorder), pen lifter relay 58 and relay 49 to earth. Relay 18 thus locks on and the calling button 52 can be released. A.C. is also supplied via lines 96 and 94, B contacts of the calling button (now released), pen lock-out solenoid 59 and lines 63 and 61, enabling the pen to be removed from its home position for writing to commence. At the remote recorder the relay contacts C energize the transformer 68 via lines 69 and 71, supplying power, to the X and Y amplifiers; these receive the input modulated signals coming along wires 55, 56, the appropriate halfcycles being separated by the diodes 74, 75. The amplifier outputs control motors (of the galvanometer type) 78, 79 which move the recorder pen 83 through the pantograph arms 81, 82. When the transmitter platen is depressed the switch 39 opens and resistor 85 is inserted in the D.C..path, allowing relay 58 to release but still holding relay 18. Paper feed is controlled by the motors 86, .87 and the clutch 88, energized by wires 89, 91, the return being through either the wire 92, B contacts of switch 37, wire 93, B contacts of call button 52 and wires 94, 95, or the cam-switch 95 and wire 96. Thus on commencement of a message switch 37 is depressed to energize the motors and start the paper feed, cam 97 starts to rotate and switch 95 maintains current through the motors after downward pressure on the pen is released; the cam completes one revolution for one frame of paper. At the recorder similar motors 99, 101 and clutch 102 are energized via the contacts of the relay 58 (now released as resistor 85 is in circuit), pen arm switch 104 (closed as recorder pen is in home position) and C contacts of relay 49. As at the transmitter the cam-switch 110 closes when paper feed commences and maintains the current even if relay 58 should be energized; this cam also makes one revolution per frame of paper. At the end of a message the operator initiates the paper feed and leaves the pen 12 in the home position so that switch 111 opens. When cam 98 has completed one revolution it will then open switch 44, thus deenergizing relay 18 and consequently releasing relay 49 also. The recorder is then returned to the stand-by position, paper switch 112 will close and the lamp 113 will light to indicate that the message is finished. At the transmitter the de-energization of relay 18 removes the supply from the solenoid 59, thus locking the pen in the home position. The pair of lines L1, L2 could be replaced by separate wires for pen-movement and control signals, with a separate earth return. The B contacts of relay 49 and the associated contact of relay 58 ensure that the latter is always energized before the former, so that the pen magnet 59 operates to free the transmitter pen before power is available to move the recorder pen.