PURPOSE: To prevent uneven coating and uneven density by blast treating the surface of a member for triboelectrifying a toner with a substance triboelectrifiable in polarity same as the toner.
CONSTITUTION: A multipolar permanent magnet 9 is fixed nonrotatably, and a nonmagnetic cylinder 4b covering the magnet 9 rotates in the same direction of an electrostatic image bearing face 1 and its surface for carrying a developer is blast treated with a substance chargeable in polarity same as the toner. A one- component type insulating magnetic developer fed from a developer hopper 11 is spread on the nonmagnetic cylinder 4b and the toner particles are given an electrostatic charge opposite in polarity to an electrostatic image charge by friction between the cylinder 4b face and the toner particles. Such treatment stabilizes toner chargeability even in low humidity as compared with an untreated state, and uneven coating and uneven density can be prevented.
MIHASHI YASUO
MURAKAWA KAZUNORI
OKADO KENJI
