Single pass color printer having improved process and slow registration

Claim 1

An imaging system for forming image exposure frames on a photoreceptor belt moving in a process direction during a single pass including: a plurality of Raster Output Scanners (ROS) units, each ROS unit generating image-modulated scan lines which are transmitted along an optical path to form said image exposure frames, said ROS units located in a common housing and positioned symmetrically on opposite sides of two polygon scanners mounted vertically on a common rotating shaft, said ROS units each comprising: a diode laser for generating a beam output, means for modulating the beam output of said laser with input video data, optical means for collimating and expanding the modulated laser beam output and directing the collimated and expanded output against an associated polygon scanner, post polygon lens group for correcting fθ and distortion in the reflected beam thereby producing a corrected scanning beam, a 90° roof mirror assembly mounted on a movable mirror carriage which folds the corrected scanning beam from the post polygon lens group in a 180° path reversal and a folding mirror for directing the corrected scanning beam out of the common housing and onto the photoreceptor belt, each scanning beam being parallel to each other, the improvement wherein said roof mirror carriage is integrally mounted to a focus carriage and secured to the common housing at a position providing an optically focused scan line at the photoreceptor belt surface, means for incrementally moving, said roof mirror carriage to provide a skew registration correction to the scan line at the photoreceptor belt surface, and to provide a process registration direction correction to the scan line at the photoreceptor surface;