PURPOSE: To decrease splashing of a toner from a developing tank by controlling the rotation speed of rollers in the developing tank when rotation of rollers is started and stopped in a manner that the rotation speed is slowly and continuously changed from the rotation speed in the developing period.
CONSTITUTION: Rollers in the developing tank, especially, stirring rollers 32, 33 and developing roller 34 in a developing case 35 are controlled in a manner indicated by the time-rotation speed diagram. In the diagram with axis of abscissas for time and the axis of ordinates for rotation speed, the rotation speed during starting rotation in period t1-t2 for magenta developing is continuously increased to the constant speed Vc for development in period t2-t3 and then rotation is decreased in period t3-t4 from Vc to zero. Thereby, drastic change of the rotation in the starting and stopping periods is prevented, which decreases splashing of the toner. Thereby, mixing of toners in a developing device even when the copier contains lots of color toners is prevented, and thereby, reproducibility of colors can be improved for full-color copies and the inside of the machine is not contaminated with toners.
KAZAKI YUUICHI
KAWAMOTO HIROSHI
NISHIMURA HIDEYUKI
MAEDA YASUTAKA
