Patent GB-680661-A (GB)
Title: Multi-stylus facsimile machines
IPC: H04N1/00
Filed: 1950-03-24
Abstract: 680,661. Copying-telegraphy. STANDARD TELEPHONES & CABLES, Ltd. March 24, 1950 [March 25, 1949], No. 7431/50. Class 40 (iii). In a facsimile receiver or transmitter, a plurality of styli mounted at equal intervals along a travelling metal band are positively guided in such manner that successive stylus points are constrained to follow absolutely coincident paths whilst in contact with a resiliently-mounted electro-sensitive message sheet employed for reception or transmission. In one arrangement each stylus is mounted in a holder soldered to the metal band, and in a modification, the socket for a stylus is formed in a spring tab riveted to the metal band. The point of each stylus is adjusted in relation to the sheet to be scanned by a gauge forming part of the machine. The metal band 82 provided with supports 93 carrying the styli 90 is driven by a grooved wheel 67 and passes over an idler wheel 79 which is adjustable to vary the tension of the band 82 and pins 83 in the two wheels engage holes in the band to prevent slippage. The driving wheel 67 is rotated through a friction clutch K by a worm-wheel 36 and worm 43 driven by an electric motor when a stop-disc 45 secured to the shaft 27 is released by the movement of the armature 59 when the magnet is energized. The movement of the armature also closes contacts, Fig. 11b (not shown), which temporarily reverse the voltage applied to a line leading to a distant transmitter. Adjacent a platen 154 and corresponding to the line to be traversed is mounted a member 99 carrying channel members 102, 103 which engage the sides of the band 82 and a bar 108 with bevelled end portions 108<1> engages the operative stylus so that a predetermined line is traced on the paper 134 by the point 96 of the stylus. The receiving paper 134 is mounted on the substantially plane platen member which is pivoted at 157 and biased anticlockwise by a spring 164. The top portion of the platen has a channelled portion 162 forming a groove 163 opposite the operative traverse of the stylus points and a spring blade 167 adjustable by a cam 169 acts to damp the vibration of the platen. The paper is fed from a roll 128 by a rubber-covered feed roller 142 driven by gears 149, 150 from a small synchronous motor 152. The marked. paper is fed through a slot formed by spaced members 171, 172, the former having a knife edge 171<1> for severing the recorded sheet. To obtain recorded message sheets of predetermined length the sheet can be fed, after recording, by a hand wheel 176 carrying a sprocket connected by a chain to a sprocket on the shaft of the feed roller 142. When the message sheet approximates its correct length a cam projection carried by the shaft 177 operates a switch member to extinguish a lamp and the wheels are rotated until a mark 188 registers with a marking on the casing of the enclosure corresponding to the predetermined length of message sheet. A gauge member 195 is slidable on pins 199, 200 to position a surface 208 for the corect setting of the points of the styli 90, and is returned to its inoperative position by pins 73 on the driving wheel 67. An arm 211, Fig. 9, carrying a roller 213 in engagement with the paper roll 128, operates a switch 215 to illuminate a lamp, Fig. 11a (not shown), when the paper supply is nearly exhausted. A rotatable brush 192 removes particles of dust, carbon, &c. from the stylus members 90 before they traverse the paper 134. A modified construction of platen is described in connection with Figs. 22-25 (not shown), in which a wire member for guiding the paper is disposed above the path traversed by the stylus and is substituted for the guide strip 159, Fig. 16, which has the defect of collecting particles of dust, carbon, &c.