| 摘要 |
PURPOSE:To prevent toner splashing and to improve fine line reproducibility by satisfying specific conditions disposing the main pole position of the developing magnetic pole in a sleeve on the upstream side in the rotating direction of the sleeve and constituting alternate magnetic fields between the sleeve and a carrying member. CONSTITUTION:The relation of the expression I is satisfied and the position of the main pole N1 of the magnetic pole in the developing sleeve 11 is disposed near the upstream side in the rotating direction of the sleeve than the position 13 where the electrostatic latent image carrying member 12 and the sleeve 11 are in the extreme proximity to each other so as to correspond to the region where the magnetic flux density decreases increasingly toward the downstream side to the position 13. The AC voltage which is of the same polarity as the polarity of the electrostatic latent images and forms the alternate electric fields between the max. and min. potentials is impressed between both. In the expression I, M is the coated amt. (g/cm<2>) of the developer 15 per unit area of the sleeve; H is the distance (cm) at which the carrying member 12 and the sleeve 11 are in the extreme proximity to each other; T/D is the weight fraction (%) of the concn. of the toner in the developer 15; C/D is the weight fraction of the concn. of the carrier; Pt is the true density (g/cm<3>); Pc is the true density of the carrier. The toner splashing is suppressed in this way and the reproducibility of the high-density images, fine lines and dot images is improved. |
