Cleaning Behavior of Carriers at the Developing Stage in Cleaning-Unit-Free Process

Abstract

Influence of parameters of magnetic carriers on their cleaning characteristics was examined in an electrophotographic imaging system without cleaning unit, in which the residual toner on the photoconductor was cleaned by the carrier beads at the developing stage simultaneously. Several magnetic carriers with various saturation magnetization, shape, electric resistivity and particle size were prepared for this study, based on both iron and ferrite.
The carrier with higher saturation magnetization showed lower memory effect and better resolution by less residual toner on the photoconductor. The iron carrier with irregular shape showed better background density, which was attributable to a larger specific surface area of the carrier. The carrier with higher electric resistivity showed lower image and background densities, and gave less residual toner on the photoconductor. The recovery of residual toner from the photoconductor by the developer was independent of the electric resistivity of the carrier. The smaller size iron carrier gave a lower background density because of its high toner triboelectric charge. The recovery of the residual toner by the developer was almost independent of their particle sizes. The optimum condition for the cleaning-unit-free system was confirmed by using the irregular shape iron carrier of 30 μm in particle size.