Patent ID: 6295116
Filing Date: 2001-09-25
Classification: G06K,H04N

Abstract:
An optical scanning system for a printer, comprising:an optical scanning unit having a deflector divided into a plurality of deflection regions to allow repetitive scanning of a beam of light emitted from a light source by rotation, said optical scanning unit scanning the beam of light onto a photosensitive belt traveling around a plurality of rollers;a first photodetector installed at a position separated from an edge of the photosensitive belt, to be able to receive the beam of light scanned beyond the edge of the photosensitive belt;a second photodetector installed a predetermined distance apart from said first photodetector, to be able to receive the beam of light scanned just beyond the edge of the photosensitive belt until the beam of light hits the edge of the photosensitive belt;a first signal generator producing a scanning reference position signal when a signal output from said first photodetector in response to the reception of the beam of light and a signal output from said second photodetector in response to the reception of the beam of light have the same level;a second signal generator producing an edge pulse signal having a width corresponding to the period from the reception of the scanning reference position signal until the beam of light reception of said second photodetector is terminated; anda controller calculating a degree of deviation from a reference track of the photosensitive belt in a direction perpendicular to the traveling direction of the photosensitive belt using the width of the edge pulse signal, said controller controlling the driving of said optical scanning unit such that the beam of light corresponding to image information is emitted onto the photosensitive belt beginning from the starting point of an image print region of the photosensitive belt.