Calibration technique for test patterns from multiple color inkjet printheads

摘要

Light emitted from an obliquely angled LED source is directed by peripheral light tube walls which extend vertically toward media displaying printed indicia. The emitted light provides an illuminated area surrounding the printed indicia, while the light tube walls shield the printed indicia from excessive external light, so that a sensor measures the intensity of emitted light directly reflected from the media through a protective aperture.