Electrophotographic copier and charging means used therefor.

摘要

The invention is directed to an apparatus for electrophotographic process, equipped with a charging device of contact type using a conductive roller or brush, and the charging device used therefor. The apparatus is characterized in the following constructions: roll-shaped fiber aggregation (5) that is rotated in contact with the photoconductive surface (1) through spacing member; (5b) use as applied voltage to the fiber aggregation of periodically oscillating voltage having a lower limit exceeding the surface potential of photoconductor in the aforementioned device; a brush-type charger that is vibrated while contacted with the photoconductor surface and regulated as required; a fiber roll-type charger (5a) wherein ventilation holes (E) are disposed on the roller substrate surface; the fiber roll-type charger with holes further including a closed container with exhausting means enclosing the charger; set-up of a product of planting fiber intervals on a fiber roller and a peripheral velocity ratio of the photoconductor to the roller such that the product is smaller the average particle size of the developer used; changing application voltage to a charger roller depending transfer-treated portion or portions otherwise on the photoconductor surface; and provision of dirt preventer, aligned with the longitudinal direction to the charging roller with conductive fiber, and shiftable between contact and spaced position. Any of these can present desired effect. <IMAGE>