| 摘要 |
PURPOSE:To always obtain a stable image of high quality irrespective of environmental conditions and secular change in developer. CONSTITUTION:The environmental conditions such as ambient temperature and humidity, etc., of a developing device are detected by an environment sensor 37 in a main controlling part 31, and a developing bias electric field having a reference concentration pattern formed on a photosensitive drum 2 is controlled by the main controlling part 31 based on the detection result, and also, the reference value of a toner concentration sensor for detecting the toner concentration in the developing device is controlled in accordance with the control for the developing bias electric field, and the toner replenishment for the developing device (toner concentration) is controlled by a toner replenishment circuit 41 based on a toner replenishment signal (toner concentration controlling signal) sent from the toner concentration sensor. |
