| 摘要 |
A magnetic roller comprising a diamagnetic cylinder rotatable about magnetic poles which extend axially inside the cylinder and are each formed by similar poles of magnets lying axially beside each other is made to generate a substantially homogeneous magnetic field over its full working width, thus enabling the magnets to be made of strongly ferromagnetic, anisotropic material, by the provision, over and along one or more of the magnetic poles between the magnetic pole and the diamagnetic cylinder, of a material having high magnetic permeability, such as a strip of soft iron of between 0.1 and 1 mm. in thickness fixed to and not wider than the surface of the magnetic pole. The magnetic roller is especially useful in electrophotographic developing apparatus for transporting magnetically attractable developing powder between a powder reservoir and a developing zone in which powder from a magnetic brush formed on the cylinder is applied to electrostatic images on imagewise exposed photoconductive sheet material. |
