Patent ID: 9026011
Filing Date: 2015-05-05
Classification: G03G

Abstract:
1. An image forming apparatus comprising: a photosensitive member rotatable at a process speed of not less than 500 mm/sec; a first developer carrying member for carrying a developer comprising toner and a carrier having a volume resistivity 10 a second developer carrying member for carrying the developer received from said first developer carrying member and for developing the electrostatic image by rubbing said photosensitive member with the developer carried on said second developer carrying member; wherein said first developer carrying member is provided with a first magnetic pole at a position opposed to said second developer carrying member and a second magnetic pole having the same magnetic polarity as the first magnetic pole at a position downstream and adjacent to the first magnetic pole with respect to a rotational direction of said first developer carrying member, wherein said second developer carrying member is provided with a third magnetic pole at a position opposed to said first developer carrying member and a fourth magnetic pole having the same magnetic polarity as the third magnetic pole at a position upstream and adjacent to said third magnetic pole with respect to a rotational direction of said second developer carrying member, wherein said second developer carrying member is disposed downstream of said first developer carrying member with respect to a rotational direction of said photosensitive member; a voltage source for applying a developing bias voltage comprising a DC voltage component and an AC voltage component to said first developer carrying member and second developer carrying member; and a driving device for rotating said first developer carrying member at a peripheral speed higher than that of said photosensitive member and for rotating said second developer carrying member at a peripheral speed which is higher than that of said photosensitive member and which is lower than that of said first developer carrying member.