We propose a system to reduce electrophotographic laser printer banding artifacts due to optical photoconductor(OPC) drum velocity fluctuations. The drum velocity fluctuations are sensed with an optical encoder mounted on the drum axis. Based on the line-to-line differential encoder count, we modulate the laser pulse width to compensate fluctuations in development that would otherwise occur. We present an analysis of the system, including the compensation algorithm that determines the desired pulse-width as a function of differential encoder count. Characterization of the system is based on printing, scanning, and processing a special test page that yields information about line-spacing and absorptance fluctuations. This data is synchronized with the encoder count signal that was recorded during the printing of the test page. Finally, we present experimental results for an HP LaserJet 4M printer that demonstrate the efficacy of the system in reducing banding due to OPC drum velocity fluctuations.
Guo-Yau Lin, Jimmy M. Grice, Jan P. Allebach, George Chiu, Wayne Bradburn, Jeff Weaver, "Banding Artifact Reduction in Electrophotographic Printers by Using Pulse Width Modulation" in Proc. IS&T Int'l Conf. on Digital Printing Technologies (NIP16), 2000, pp 281 - 286, https://doi.org/10.2352/ISSN.2169-4451.2000.16.1.art00073_1