Raster output scanners

摘要

Described herein is a raster output scanning system (10) which includes a photoreceptive drum (24) rotatably driven in a process direction by a drive unit (27). A modulated light beam unit (13) is scanned horizontally across the rotating drum (24) to construct a latent electrostatic image. To determine vertical positioning errors during each horizontal scan, an error feedback unit (18, 19) for determining light spot position error on the rotating drum (24) is used. To correct for any determined vertical mispositioning, the error feedback unit (18, 19) is connected to a mirror (15) positioned adjacent to the modulated light beam unit (13). The mirror (15) is electrostatically or electromagnetically pivotal to vertically adjust position of the light spot in a vertical process direction during each horizontal sweep thereof. <IMAGE>