Developing device and image forming apparatus

摘要

A developing device includes a first magnet fixed inside a first developer bearing member and including a pair of first repulsion magnetic poles with the same polarity and disposed adjacent to each other, and a second magnet fixed inside a second developer bearing member and including a pair of second repulsion magnetic poles with the same polarity and disposed adjacent to each other. The first magnet has a magnetic flux density distribution of a normal component of the first developer bearing member in the circumferential direction of the first developer bearing member having only one minimal point between the pair of first repulsion magnetic poles, and the second magnet has a magnetic flux density distribution of a normal component of the second developer bearing member in the circumferential direction of the second developer bearing member having a plurality of minimal points between the pair of second repulsion magnetic poles.

主权项

1. A developing device, comprising:
a first developer bearing member configured to bear developer including non-magnetic toner and magnetic carrier and to develop an electrostatic latent image at a first developing region; a second developer bearing member disposed oppositely to the first developer bearing member, which is configured to bear the developer delivered from the first developer bearing member and to develop the electrostatic latent image at a second developing region; a first magnet fixed inside the first developer bearing member, which is configured to make the first developer bearing member bear the developer on the surface of the first developer bearing member, the first magnet including a pair of first repulsion magnetic poles with the same polarity as each other, the first repulsion magnetic poles being disposed adjacent to each other; a second magnet fixed inside the second developer bearing member, which is configured to make the second developer bearing member bear the developer on the surface of the second developer bearing member, the second magnet including a pair of second repulsion magnetic poles with the same polarity as each other, the second repulsion magnetic poles being disposed adjacent to each other, wherein the first magnet is configured such that a magnetic flux density distribution of a normal component of the first developer bearing member in the circumferential direction of the first developer bearing member has only one minimal point between the pair of first repulsion magnetic poles, and wherein the second magnet is configured such that the magnetic flux density distribution of a normal component of the second developer bearing member in the circumferential direction of the second developer bearing member has a plurality of minimal points between the pair of second repulsion magnetic poles.