Bi-cell chevrons detection color registration system for color printing

Claim 1

In a plural color reproduction apparatus with a color registration system for the registration of plural color images on an image bearing surface movable in a process direction, which color registration system generates on said image bearing surface chevron shaped registration marks with opposingly angled legs at an angle to said process direction, and which color registration system further includes at least one registration marks sensor for detecting the positions of said chevron shaped registration marks on said image bearing surface, said registration marks sensor having chevron shaped optical sensing areas with opposingly angled legs at substantially the same opposing angles as said chevron shaped registration marks on said image bearing surface, the improvement wherein: said chevron shaped optical sensing areas of said registration marks sensor comprise a matching pair of paced apart elongated bi-cell detectors in a generally chevron shaped pattern, each of said spaced apart elongated bi-cell detectors has a parallelogram shapeed optical sensing area, and said parallelogram shape of each said bi-cell detector optical sensing area is defined by elongated parallelogram sides extending at the same angle as one said leg of said chevron shaped registration marks on said image bearing surface, and parallelogram ends which are parallel to said process direction, so as to provide higher color registration accuracy.