| 摘要 |
PURPOSE:To form a stable and high quality image and to decide an accident exactly, by detecting density of the toner image of a reference target in order to control conditions for image formation and also displaying the case of exceeding a control limit. CONSTITUTION:The toner image of a reference target 3 is formed beyond the effective copying region of a photoreceptor 6, and toner density is detected with a detector 10, such as consisting of a light emitting device 10a and a photodetector 10b. The detected density is compared with a reference value, and a developing bias circuit, an exposure lamp control circuit, a toner feed control circuit, a charge current control circuit, etc. are controlled with CPU or the like to control image formation conditions in order to form a high quality stable image. On the other hand, in the case of exceeding a controllable limit, the accident is displayed with CPU or the like, the disorder is decided exactly, permitting necessary countermeasures, such as toner replenishment to be taken. |
