| 摘要 |
PROBLEM TO BE SOLVED: To prevent an image defect from occurring by always keeping the thickness of a toner layer proper in an electrophotographic device. SOLUTION: A fixed magnetic roller, equipped with a plurality of magnetic poles, is included in a non-magnetic rotary developing sleeve, and a magnetic blade is arranged to be opposed to one of the magnetic poles of the fixed magnet roller on an upstream side in the rotating direction of the rotary developing sleeve from a position which most proximate to an exectrostatic latent image formed on a photoreceptor drum. A magnet, having the magnetic pole whose polarity is the same as the magnetic pole of the fixed magnet roller facing the magnetic blade, is attached to the magnetic blade. Defining that the flux density (mT) of the magnetic pole of the fixed magnet roller opposed to the magnetic blade to be TA, the flux density (mT) of the magnet attached to the magnetic blade to be TB, the ten-point surface roughness (μm) of the rotary developing sleeve is RZ and a map (mm) between the magnetic blade and the rotary developing sleeve is GBS, TA>TB is set, and also relation between TA, TB, RZ and GBS is set to 0.017<=(RZ×GBS)/(TA+TB)<=0.025. Thus, the thickness of the toner layer is always kept proper.
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