Print ribbon driving mechanism

摘要

A print ribbon driving mechanism including a switching bail swingingly mounted on a reciprocatively mounted support movable between two opposite spindles carrying print ribbon spools. The spindles have ratchet teeth, and the switching bail has a pair of opposite pawl surfaces for engaging the ratchet teeth as the support and bail are moved in opposite directions. A trigger lever is provided on each of the spindles which is responsive to the existence of ribbon on the associated spools so that the trigger lever drops into an operative position on depletion of the ribbon from the associated spool, and the switching bail is provided with two opposite camming surfaces adapted to engage the trigger levers in their operative dropped positions for swinging the switching bail into a position to engage the ratchet teeth of the spindle of the dropped trigger lever so as to wind ribbon onto this particular spool.