US Patent 7643678 Streak compensation with scan line dependent ROS actuation

Xerographic machines can print documents that have unintentional streaking parallel to the process direction. There are many possible source of the streaking. Currently, the streaking is minimized by using a cross process direction dependent modulation, called a profile, to modulate a modulated light beam being scanned across the photoreceptor. The profile is purely a function of cross process direction position. The profile can minimize, and often eliminate, streaking for any one area coverage, but only for that one area coverage. Different profiles can be produced that work best for different area coverages. Choosing a profile from a group of profiles for use with each scan line can minimize parallel streaking for a wider range of area coverages.