Patent ID: 7406280

Claim:
A developing device comprising: a developing roller having a magnet roller configured to transport developer to be used in developing an electrostatic latent image; a regulating member configured to regulate an amount of the developer transported to the electrostatic latent image with the development roller; a reflux plate configured to reflux excess developer regulated by the regulating member away from the regulating member; and a rubbing member arranged to face the developing roller at a second gap which is larger than a first gap defined by the developing roller and the regulating member, wherein the rubbing member is configured to rub developer transported to the first gap in order to create friction prior to preliminary electrification of the developer; and wherein the magnet roller has a plurality of magnetic poles arranged in circumferential direction thereof and one of the magnetic poles is provided so that a polar central axis thereof faces the second gap and the polar central axis is positioned between the regulating member and a position upstream of a direction of developer transportation that is 1.5 degrees from a minimum position of the second gap; and wherein the second gap G 2 (mm) G 1 <G 2 ≦0.8×Dm, where G 1 is the first gap (mm) and Dm is a width of magnetic pole (mm).