| 摘要 |
PURPOSE:To avoid problems of ground fogging or low density even when environment changes so as to obtain an appropriate image by providing a control means, which controls the size of a developing bias electric field impressed between a developer supporting body and an image carrier based on signal from an environment detecting means. CONSTITUTION:The environment detecting means 19, constituted of a humidity sensor and a temperature sensor, is provided at the position in the environment where the higroscopic condition of toner is well reflected, in the vicinity of a developing device or a toner replenishing device, and information signal from this environment detecting means 19 is fed to a control means 18. The control means 18 controls an effective value for AC of a developing bias electric source 1', corresponding to the information signal from the environment detecting means 18. Thus, even when the environment changes, problems such as ground fogging or low density do not generate and a stable image can be obtained. |
