| 摘要 |
PROBLEM TO BE SOLVED: To prevent suction and void and to stably form a high-quality image by applying the developing bias voltage obtained by superposing AC voltage on DC voltage between a developer carrier and an image carrier. SOLUTION: A gap between a developing sleeve and a photoreceptor in a developing area is made larger than the thickness of a developer layer, and the AC voltage VAC is superposed on the DC voltage VDC and applied between the developing sleeve and the photoreceptor. The DC voltage VDC, the electrification potential VH of the photoreceptor and the electrification potential of toner have the same polarity, and the toner, to which a chance to separate from carrier at the AC voltage VAC is given, does not adhere to the electrification potential VH part of the photoreceptor where absolute potential is high but adheres to a latent image potential VL part where it is low, so that an image is developed. In the case of applying a blank pulse to the developing sleeve, the attenuation of toner flying speed is a little and hardly goes along the bent line of electric force in a blank part, and the toner easily adheres even to a low density part, then the suction is prevented and the bound of the toner on the image carrier is restrained, so that the void is prevented. |
