| 摘要 |
PURPOSE:To obtain a simple developing device which can prevent deterioration of a developing agent caused by the difference of copies in size and improve density variation of copies, by making magnetic fields different from each other between an area where developing agent consumption is high and another area where the consumption is low. CONSTITUTION:This developing device is designed so as to prevent deterioration of a developing agent by making the magnetic circulation of the developing agent in an area where developing agent consumption is low weak in degree and the peak position of the magnetic pole (Pole S2) of a fixed magnet 3 controlling the circulation of a magnetic developing agent 4 in a hopper in the axial direction of a sleeve is changed. This magnetic pole S2 is formed so that the magnet roll 3 can have different magnetic-pole constitutions which are shifted in the peripheral direction between the central part and both end sections. Since the inter-magnetic-pole angle between both end sections of the magnetic pole S2 and another magnetic pole N1 is larger than that at the central part of the magnetic pole S2, the circulating speed of the developing agent in a hopper at both end sections of the nonmagnetic sleeve 2 becomes slower than that at the central part. |
