Toner satellite formation in electrostatically transferred images

The tendency of toner particles from electrophotographically produced dots and alphanumerics to fly apart during electrostatic transfer was investigated using an ultracentrifuge and an electrostatic detachment cell. It was found that the forces needed to detach a toner particle from a photoconductor were far greater than those that could be applied electrostatically, for all but a few of the particles, either before entering or upon exiting the nip formed by a transfer roller contacting the photoconductor. This suggests that the majority of toner satellite formation should not occur due to toner particles jumping the air gap present in either the pre or postnip regions around the transfer roller. However, it was also found that the forces needed to move toner particles on the photoconductor were at least an order of magnitude less than those needed to detach the particles. This result suggests that toner satellites may be formed by components of the electrostatic transfer forces tangent to the surface of either the photoconductor or receiver or by mechanical forces that move the toner on the substrate either before or after transfer, rather than by inducing the toner to jump across an air gap.