Patent ID: 6959163

Claim:
A developing device comprising: a developing container for containing magnetic toner; first and second toner carrying members for carrying the toner in said developing container toward first and second developing zones to develop an electrostatic image on an image bearing member, respectively, by rotation thereof in a same rotational direction, a layer thickness of the toner carried on said second toner carrying member being regulated by said first toner carrying member; a first magnetic member, provided in said first toner carrying member, for generating a magnetic field, said first magnetic member having a first magnetic pole disposed at a position so as to be substantially opposite to the image bearing member and a second magnetic pole disposed at a position so as to be substantially opposite to said second toner carrying member and having a polarity opposite to a polarity of said first magnetic pole; and a second magnetic member, provided in said second toner carrying member, for generating a magnetic field, said second magnetic member having a third magnetic pole disposed at a position so as to be substantially opposite to said first toner carrying member and having a polarity that is the same polarity as the polarity of said first magnetic pole, wherein magnetic flux densities A, B, and C of said first magnetic pole, said second magnetic pole, and said third magnetic pole, respectively satisfy: | A|>|B|>|C| where |A| is not less than 80 mT, and |B| and |C| are not less than 50 mT.