Patent 7473509 was granted and assigned to Konica Minolta on January, 2009 by the United States Patent and Trademark Office.
A toner image is formed while a developing sleeve is rotated in a direction counter to that of an organic photoreceptor at the developing section and a surface layer of the organic photoreceptor contains metal oxide particles which have a number average primary particle diameter of 3 to 150 nm and are chosen from metal of the 3rd or 4th cycle of a periodic table.