Halftone banding reduction for a class of electrophotographic systems – Part II: Closed-loop control

A new control configuration for laser printing process was proposed, which constructs a feedback controller for regulation of the motor/gear transmission subsystem using direct velocity measurement from the imaging component. Causal connection between banding artifact and transmission errors has been demonstrated previously. Two controller design approaches were suggested for reducing banding artifact. The proposed designs were based on the internal model principle and H∞ robust control theories, both have two degree of freedom control structure. The controllers were implemented on a monochrome laser printer, for which latent images are formed on a cylindrical photoconductor drum. Experimental results showed significant reduction in the measured velocity error for the photoconductor drum as well as noticeable banding reduction on the printed images.