| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus, even if a preferential image is changed, which can deal with this. <P>SOLUTION: A development roller 27 is provided with: a multipolar magnetization member 35 of multipolar magnetization; and a nonmagnetic sleeve 36 externally fitted to the multipolar magnetization member 35 freely rotatably. In the multipolar magnetization member 35, magnetic poles 41 to 45 composed of bar magnets with rectangular cross-sectional shape are radially arranged so as to be separated from each other at a plurality of circumferential positions. A photosensitive drum 21 is provided with a counter magnetic pole 46 having the same polarity as that of the main magnetic pole 41 and made of bar magnets with rectangular cross-sectional shape at the inside space thereof. The counter magnetic pole 46 faces the main magnetic pole 41 with a photosensitive layer interposed, and is composed so as to be changeable from the closest position P closest with the main magnetic pole 41 to a separated position Q separated from the main magnetic pole 41 in such a manner that the rotary axis 47a is angularly displaced by 90 degrees. <P>COPYRIGHT: (C)2010,JPO&INPIT |
