GB963545A - Improvements in or relating to typewriting and like machines - Google Patents

Abstract

963,545. Typewriters. IMPERIAL TYPEWRITER CO. Ltd., and A. B. PATEMAN. March 22, 1962 [March 22, 1961], No. 10486/61. Heading B6F. Ink-ribbon mechanism.-A typewriter of the kind comprising a cylindrical platen 14, Fig. 1, and a plurality of types movable individually to a striking position in which they may strike a master sheet held over the platen, is provided with a hectograph ink ribbon 44 which is guided in a transverse direction to the stepwise movement of the sheet in a letter space direction, and the ribbon is advanced in the said transverse direction each time a type loaves the striking position. The ink ribbon 44 is fed from the supply spool 42, Fig. 2, with the dressed side of the ribbon facing inwardly, over guide rollers 57 on the ribbon guide 43, Figs. 1 and 2, over a guide roller 57a into a channel shaped guide member 51, and the ribbon then passes around the platen 14, into channel shaped guides 56 with a roller 58 (Fig. 4, not shown) and over guide rollers 57, through a nip between a serrated and drive sheet, 92 and 86, respectively, on to a take-up spool 41. The rubber covered drive wheel 86, Fig. 1, is driven stepwise from the escapement rack 16 engaging a pinion 71, mounted on a shaft 69 carrying a pawl 73 and ratchet 74, and the associated sprocket wheels 79, 82 and chain 81, the pawl and ratchet mechanism providing a unidirectional drive for the ink ribbon so that when the carriage 12 is moved from left to right the ratchet 74 will not transmit a drive. Similarly, when a tabulator key is depressed or a release lever 17 is operated the carriage rack 16 will be moved out of engagement with the pinion 71 and the ink ribbon will not be advanced. The ribbon is advanced by engagement of the wheel 86 and serrated wheel 92 and is taken up on the spool 41, driven by a friction clutch including friction plate 64 and spring 65. The ink ribbon guide 43, Fig. 1, which is mounted on a support plate 37 by a boss member 47, comprises a pair of tubular members 45 provided with a guide plate 48, from which depend the lower and upper ink ribbon guide members 51 and 55, respectively, and the ink ribbon guide assembly carries a set of ink ribbon guide rollers 57, 57a, 57b and 58. Sheet feeding, guiding and chain plug.-A front and a rear set of paper feed rollers 18, 19, Fig. 5, are provided on the carriage 12 and each set comprises a shaft 21 rotatable about a fixed axis on the carriage 12 and a movable shaft 22 rotatably mounted on a pivotal link 20 and carrying a lever 104 which is provided with a nose 105 to engage the fixed shaft 21 and move the shaft 22 away from the fixed shaft to separate the rollers 18, 19 mounted thereon. The master sheet is then inserted between the spaced apart rear feed rollers, which are then re-set to engage the sheet and advance it through paper guides 28, 32 and a further set of guides 35, Fig. 1, into the front set of paper feed rollers 18, 19. The two sets of paper feed rollers are simultaneously operated by a platen gear-wheel 23, engaging idler wheel 24, which operates the gears 26 and 25, 27 of the front and rear sets, respectively. The paper guides are arranged to hold the master sheet away from the ink ribbon except at the striking position.