Development process for an electrophotographic duplicator employing magnetic toner

摘要

A development process for an electrophotographic duplicator using magnetic toner and a photosensitive material selected from the group consisting of selenium, organic semiconductor, and cadmium sulfide. The magnetic toner is transferred in a maximum thickness of 1.5 mm onto a cylindrical non-magnetic sleeve enclosing a magnetic roll. The magnetic force of the roll on the sleeve is in the range of from 300 to 1000 gauss and the toner comprises magnetite in the range of 40 to 70 percent by volume and has a volume specific resistivity higher than 107 ohm-cm and a granulometric measure of less than 30 mu m. A surface potential is applied in the range of from 300 to 1200 volts on the photosensitive material formed on the surface of a rotatable drum-shaped member. The magnetic toner is continuously conveyed to a development section of the photosensitive material during rotation of the member for brushing the toner in contact with the photosensitive material. The distance between the sleeve and photosensitive material is set as equal to or smaller than the maximum thickness of the transferred toner. Subsequently the toner on the photosensitive material is electrostatically transferred to a recording sheet.