Apparatus for driving and tensioning a printing ribbon for a printer

摘要

A ribbon driving and tensioning apparatus includes a pair of identical mechanical assemblies connected to reversibly drive associated rollers which support a printing ribbon. Each assembly includes a bi-directional DC reduction motor the output shaft of which is connected through a friction clutch assembly to the supporting shaft of a roller. The roller shaft includes a brake for applying a resisting torque in a direction opposite to that of the shaft rotation. A switching assembly for reversing the current to the motors and thereby reverse the direction of drive of the motors includes a pair of reversing switches mechanically coupled to a lever adapted to be pivoted between a first and a second position by a strip actuator positioned on the ribbon. A strip actuator is positioned adjacent opposite ends of the ribbon such that the direction of travel of the ribbon is reversed when the ribbon is almost completely unwound from one of the rollers.