A developing apparatus in which a first magnet of a first developing sleeve includes a first magnetic pole near a potion opposing to an image bearing member, and a second magnetic pole being downstream of the first magnetic pole; and a second magnet of a second developing sleeve includes a third magnetic...http://www.google.es/patents/US7653336?utm_source=gb-gplus-sharePatente US7653336 - Developing apparatus featuring multiple magnetic rollers for developing a latent image multiple times
Developing apparatus featuring multiple magnetic rollers for developing a ...
