IMPROVED BI-CELL CHEVRONS DETECTION COLOR REGISTRATION SYSTEM FOR COLOR PRINTING

摘要

In color printing with a color registration system for the registration of plural color images on an image bearing surface, such as a photoreceptor belt of a color printer, chevron shaped registration marks are imaged on the image bearing surface, which registration marks correspond to the color images and are sensed by a registration marks sensor as the image bearing surface moves in its process direction. The registration marks sensor has chevron shaped optical sensing areas provided by a matching pair of spaced apart elongated bi-cell detector s in a generally chevron shaped pattern. Each of these spaced apart elongated bi-ce ll detectors has a parallelogram shaped optical sensing area. That parallelogra m shaped sensing area is defined by elongated parallelogram sides extending at the same angle as one leg of the chevron shaped registration marks, and parallelogram ends which are parallel to the process direction, so as to provide higher color registration accuracy.