| 摘要 |
Provided is an image forming apparatus ( 1 ) having polygon mirrors ( 82 ) each forming an electrostatic latent image by scanning a photoconductive drum provided in an image forming unit ( 50 a , 50 b); and polygon motors ( 80 ) each driving and rotating the polygon mirror, the image forming apparatus ( 1 ) forming an image by superposing toner images formed on the photoconductive drums one on another, the toner images corresponding to the electrostatic latent images. In the image forming apparatus ( 1 ), the polygon mirror ( 82 ) of the image forming unit ( 50 a , 50 b) is so formed as to have facets whose number is other than a multiple of the number of poles of the polygon motor ( 80 ), such that a plurality of stable phase states can be obtained. A driving stop period (T) is provided, such that, if a predetermined amount of phase shift in a subscanning direction is observed between the scanning positions of the polygon mirror (second polygon mirror) of the image forming unit ( 50 a) and the polygon mirror (first polygon mirror) of the image forming unit ( 50 b), the driving of the polygon mirror (first polygon mirror) of the image forming unit ( 50 b) is stopped for a predetermined duration, and is then resumed in another stable phase state.
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