| 摘要 |
PURPOSE: To make color balance and color reproducibility excellent by controlling developing bias so that image density to specified potential difference between the DC component of the developing bias and the potential of an electrostatic latent image may be higher in a more succeeding image forming stage. CONSTITUTION: The circumferential speed of a developing sleeve 29 is controlled to fixed speed with reference to the circumferential speed of an image forming body 1 by a speed control means. Developing bias consisting of the DC component and an AC component is impressed on the developing sleeve 29 so as to perform development. Among the elements of the developing bias, the frequency and the amplitude of the AC component are controlled in every image forming stage by a developing bias control means. The frequency of the AC component of the developing bias is changed to the lower frequency in the more succeeding stage by a developing bias control means so that the image density to the same developing contrast may be higher, that is, so that developing weight may be larger in the more succeeding image forming stage in the image forming stage repeated plural times. |
