| 摘要 |
PURPOSE: To stably and accurately detect the toner concentration information of the developer or the developing information of a developing area of a developing device by providing a detecting means detecting the toner concentration of a developer layer and developing state by projecting light on the side of the developing roller of the developing device on the outer surface side and receiving reflected light, on the inner surface side of an image forming body. CONSTITUTION: The optical detecting means 6Y to 6K of the toner concentration constituted of a light projecting means projecting the light toward the developing roller surface of the developing devices 5Y to 5K and a light receiving means receiving the reflected light from the side of the developing roller surface and obtaining the toner information of the developer layer on the developing roller surface are disposed at a common supporting body 6. Then, the toner concentration of the developer layer on the developing roller is detected by the detecting means 6Y to 6K based on a condition where the developing rollers of the developing devices 5Y to 5K are rotated for every color developing forming process and also a toner image is not formed on the outer peripheral surface of the image forming body 1 between the developing roller and the detecting means 6Y to 6K. Then, toner replenishment from toner replenishing containers 50Y to 50K to the developing devices 5Y to 5K is controlled based on its information. |
