Dielectric variation in paper and its effects on print density mottle in electrophotographic printing

Print density mottle of the solid black images in electrophotographic printing is related to paper structure. We found that mottle in commercial papers has a strong correlation with PCC filler distribution, but a very weak correlation with the overall visual formation. We explain these observations using a new mathematical model that simulates the electrostatics of toner transfer. Simulations show that print density mottle is strongly influenced by spatial variations in the dielectric permittivity of paper, which is primarily controlled by the filler distribution, and to a lesser extent by visual formation.