PURPOSE: To stably carry out printing of more than three colors without any fringe developing by setting the height of napping of developing material to be below the distance between a developing roller and an electrostatic image forming member and impressing voltage to the developing roller.
CONSTITUTION: After a first electrostatic image on the electrostatic latent image bearing body 1 is developed with toner, as a second or a third developing method, a second developing onwards is carried out without giving turbulence to a first or a second image by setting the napping height of at least one of a two component developer to be equivalent to the distance between the developing roller 7 and the electrostatic latent image bearing body 1 or to be lower. Furthermore, by impressing DC or AC voltage with DC component on a developing roller as developing bias, the good image of high developing efficiency in the second or a third developing can also be obtained. As the two component developer utilized here, it is desirable to utilize a carrier with a small toner retaining force and a low magnetic force in order to accelerate the turbulent effect of AC bias.
FURUYA NOBUMASA
NOAMI TSUNEO
