Optically controlled multi-color impact printer

摘要

An inherently rugged multi-color dot matrix impact printer having a yoke type optical code detector assembly mounted on the neck portion of an impact dot matrix print head through which a multi-colored print ribbon passes. The print ribbon is configured in alternating vertical segments of selected colors of ink which have top and bottom photo-optical code regions on the outer edge of the ribbon. Coding comprises the presence or lack of an aperture in the form of a hole which is adapted to pass light therethrough and which is aligned with each ink segment. The yoke additionally includes upper and lower light emitter/sensor pairs for sensing the coded aperture pattern to control the presence of a predetermined colored segment of printing ribbon in front of the print head.