| 摘要 |
PROBLEM TO BE SOLVED: To prevent toner from being scattered even when a primary electrifying bias is changed. SOLUTION: To stabilize developing property, etc., the primary electrifying bias is sometimes changed according to an atmospheric temperature, atmospheric humidity, the number of image forming sheets or the like. As mentioned above, since the electrifying potential (dark part potential) VD on the surface of a photoreceptor drum 1 is changed when the primary electrifying bias is changed, a potential difference between the electrifying potential VD and a primary transferring bias is changed, a transfer current is changed at a non-image part, a toner is scattered and a defective image is caused by the change of hue. In order to prevent it, an electrifying bias power source 20 and a transfer bias power source 19 are controlled by a CPU 18 so that the potential difference between the electrifying potential VD and the primary transferring bias is substantially kept constant even when the electrifying potential VD is changed by changing the primary electrifying bias. Thus, the toner is prevented from being scattered. |
