| 摘要 |
PURPOSE:To improve the ability in development and to secure the ability to remove toner sticking on a background part by making the angle of the main pole on the side of the most downstream developing sleeve larger than the angle of the main pole on the side of any other developing sleeve. CONSTITUTION:When an electrostatic latent image on a photosensitive body 4 is developed by a developing sleeve 6, the main pole angle thetaa of the fixed magnet 9a in the sleeve 6 is nearly 0 deg.. Further, the center of the peak of the magnetic flux density distribution 20 by the magnet 9a is positioned on the perpendicular from the axis of the sleeve 6 to the photosensitive body 4 and the amount of toner sticking on the photosensitive body 4 is maximum. The amount of toner sticking on the background part also increases. At the part of a developing sleeve 8, on the other hand, the main pole angle thetac of the fixed magnet 11a incorporated in the sleeve 8 is set larger than 0 deg.. Therefore, the center of the peak of the distribution 20 by the magnet 11a is slightly behind the perpendicular from the axis of the sleeve 8 to the photosensitive body 4 and it is confirmed that the toner sticking on the background part is removed. |
