GB848090A - Improvements in attachments for typewriters and like machines - Google Patents

Abstract

848,090. Ink ribbon mechanism. INTERNATIONAL BUSINESS MACHINES CORPORATION. April 25, 1957 [April 28, 1956], No. 13268/57. Class 100(4) A ribbon feed attachment for typewriters or the like has two brakes, one of which holds the ribbon stationary relative to the typewriter carriage when a printing key is pressed, the other holding the ribbon stationary relative to a fixed part of the typewriter when a function key is pressed, i.e. the ribbon is moved one letter space when printing occurs only. Depression of a typing key closes a contact, through the ribbon feed linkage, which energises brake magnets 15, 42, Fig. 3, thus a normally closed stationary brake 15 is opened and a normally open brake 42 on the auxiliary carriage, which moves with the typewriter carriage, is closed. The magnets are held in this condition by a delay condenser until the type has printed and the carriage advanced one letter space. The auxiliary ribbon, gripped by the brake 42, is thus also moved one space and a corresponding length of ribbon is pulled off a supply spool 22, Fig. 8. A frictional connection 25, 26 between spools 22 and 27 turns a take-up spool 27. The greatest outer diameter of the ribbon on the supply spool 22 is smaller than the inner diameter of the take-up device 28, backlash being taken up by a friction clutch which also keeps ribbon tension constant. When a function key is pressed, the ribbon feed linkage remains at rest and the contact is not closed. Brake magnets 15, 42 remain de-energised leaving the stationary ribbon brake 15 closed gripping the ribbon and the brake 42 open. Ribbon in the take-up device 28 is held against movement by a recoil lock 35. To remove used ribbon, a nut 36 is removed from an axle 21 and the take-up device 28 plus the ribbon is lifted by handles 32, 33, Fig 7. By pressing handles 32, 33 together adjacent ribbon gripping segments, such as 34, are opened out and the ribbon drops off. New ribbons are pulled through by the old ribbon and tensioned by holding the supply spool 22 with brake 24, Fig. 3, and turning upper spool 31, Fig. 8, until the required tension is reached. Auxiliary carriage 3, Fig. 1, carrying the ribbon in guide channel 44 may be rocked back when not in use.