Magnetic brush type developing mechanism in electrophotographic copying machine

Claim 1

A magnetic brush developing apparatus for developing a latent image on a light sensitive member with toner, said apparatus comprising a plurality of rotatable developing rolls successively disposed adjacent said light sensitive member, all said rolls being rotated in the same direction; a plurality of fixed cylindrical magnets respectively disposed within said rolls to effect movement of said toner between said light sensitive member and said developing rolls; each said magnet having a first pole directly opposed to the surface of said light sensitive member where the polarity of each first pole is opposite to that of adjacent first poles so that the development of said latent image is emphasized; each said magnet having two second poles of a polarity opposite to that of its first pole to improve the transportability of said toner, said second poles being disposed on opposite sides of said first pole and within a developing region defined between the surface of the light sensitive member and an imaginery line approximately extending through the centers of said cylindrical magnets, the angle between said first pole and said second poles being maximized to improve the development effected by each said first pole, at least some of said second poles of each magnet being substantially adjacent second poles of opposite polarity disposed on adjacent magnets, only said first and second poles being disposed with said developing region for each magnet; each said magnet having a third pole of a polarity opposite to that of its second poles so disposed outside of said developing region with respect to one of its second poles that the tendency of adjacent second poles of adjacent cylindrical magnets to undesirably affect the transportability of the toner is minimized whereby the combination of said first, second and third poles of said cylindrical magnets tends to maximize both development of the latent image and transportability of the toner.