GB543086A - Improvements in or relating to typewriter attachments for making copies without the use of carbon paper - Google Patents

Abstract

543,086. Ink-ribbon mechanism. GESER, J. R. May 6, 1940, No. 8149. Convention date, May 16, 1939. [Class 100 (iv)] In duplicating-apparatus for typewriters comprising a ribbon which is driven from the platen by means of a friction-roller and can be swung away from the printing line, the friction-roller is constantly maintained in contact with the platen by springs which are tensioned when the apparatus is mounted on the typewriter. In the apparatus shown in Figs. 2, 4 (a development), and 5, a duplicating-ribbon runs along the platen 1 and is directed by guides 6a to a pair of spools 3a each provided with a toothed wheel 5 co-operating with another toothed wheel 15 which is driven frictionally be the platen. The wheel 15 is carried by a rock-arm 17 on a yoke 22 which can rock on a stationary tube 23 and is provided with a blade spring 26 which abuts on a ridge on the tube and holds the wheel in engagement with the platen. The rock-arm 17 has a pin 19 in engagement with a slot in a rock-plate 20 having a pin 41 for co-operation with an arm 35 pivotally connected to a lever 32 in connection with a steel band 31 which is mounted in a housing 6 and is formed with a guide-slot 30a for the ribbon. The arm 35 has a tooth 36 engaging a worm 37, and abuts on a spring 38. A slide-rod 24 mounted in the tube 23 is formed with grooves 24a engaging fingers 20a on the rock-plates 20. When the ribbon has been wound off either spool, a projection 29 on the ribbon is caught by the slot 30a in the associated band 31, the latter is pulled forwards, and the catch 36 of the arm 35 is released from the worm 37. Thereupon, the spring 38 swings the arm into contact with a pin 41 on the associated rock-plate, the slide-rod 24 is shifted, and the wheels 15 are swung into and out of engagement with the wheels 5 of the empty and full spools. Spring-balls co-operate with notches in the rock-plates to hold the parts in the set position. The housings 6 are connected by a tube 53 which can rock on the tube 23. When a new sheet is placed on the platen, the housings are raised and dropped, and the worms 37 are automatically turned, to re-tension the springs 38, by co-operation of pawls on the yokes 22 with ratchet-wheels 39 on the worms. Alternatively, the arms 35 can be manipulated by knobs 51 to re-tension the springs. To prevent the ribbon from being fed during backward rotation of the platen, detents 12 are automatically moved by the platen into engagement with the wheels 5 when the platen is turned backwards. The tube 23 supports the apparatus as a unit, and is detachably mounted in brackets 45, 46 on the carriage, the bracket 45 having a yoke 48 which co-operates with a spring retaining-pin 52 in the tube. When the tube is being mounted, the rod 24 and tube are turned by means of a detachable finger-piece to tension the springs 26.