| 摘要 |
PURPOSE:To prevent toner and a carrier from being stuck to the top end part of the region to be charged of a photosensitive body by maintaining the charge potential of the top end part of the region to be charged on the photosensitive body at a low value with a charging means or an exposing means, and obtaining the step-formed charge potential distribution of the photosensitive body. CONSTITUTION:The increasing of the charge potential of the photosensitive body 9 is started at a high increasing ratio before a developing bias voltage is risen, maintained at the increasing ratio of a prescribed low value or below, in prescribed width from just before the bias voltage is risen to just after it, and then, carried out at the high increasing ratio up to a prescribed high value. Thus, the rising of the charge of the photosensitive body 9 is formed stepwise, the charge increasing ratio of the photosensitive body 9 is low before and after the developing bias is risen, C - D. Even if the timing of the charge or bias lags, the potential of the photosensitive body is prevented from being lower than the bias potential by A or above, and further, being higher than that by B or above, on the top end part, as long as the bias is risen within the ranges of (a) - (b), and the soiling of the toner and the sticking of the carrier do not occur. |
