Programming drums for document selection carriage - are rotated into given angular position by perforated web engaging teeth of pinion

摘要

The programming drums (9) for a document selection carriage are each rotated about their axis into a given angular position, via linear displacement of a film or web (13). The latter has perforations which are engaged by the successive teeth of a pinion (14) fixed to each of the programming drums (9), in accordance with the linear displacement of a cursor (12), sliding along a slot in the carriage. The web may pass around two cylinders (15) positioned either side of the programming drums (9), with a spring blade (16) maintaining the web tension. The cursor (12) can be displaced along a distance corresponding to the circumference of each programming drum (9), with a spring ratchet lever allowing it to be held in each selected position.