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BOW CORRECTION FOR LASER SCANNERS

IP.com Disclosure Number: IPCOM000026764D
Original Publication Date: 1993-Aug-31
Included in the Prior Art Database: 2004-Apr-06

Publishing Venue

Xerox Disclosure Journal

Abstract

In most designs, the laser of the printer is incident on a polygon from out of a plane containing the polygon. This geometry leads to scan bow for a typical ROS to be symmetric about the center of a scan line. Scan line bow is the displacement perpendicular to the average fast-scan direction. A graph of the displacement from a straight scan line as a function of a normalized half-scan line for a typical ROS is shown in Figure 1. Proper designs build in correction that compensate for scan bow so that the actual scan bow in the image plane is usually less than 0.030 inches. However, scan bow continues to limit the scan line width and forces compromises in the optical design in order to keep scan bow acceptably small. Although, scan bow in the 0.030 inch range is usually not a problem for single color printers, it does add complications to the registration for multiple color printers and for single pass color printers were separate scanners write each color. Scan line bow is inherent to any ROS operated out of a plane containing a scanning element.