| 摘要 |
PURPOSE:To surely stop a toner replenishment even against an irreversible trouble such as a fault of a sensor, by deciding a toner concentration control means to be abnormal, and executing an error processing, in case when a toner replenishment command from the toner concentration control means is generated continuously by the previously set number of times. CONSTITUTION:When the image density is thick, sometimes a toner replenishment command is generated continuously whenever an image is formed. However, even when the image density is the thickest for forming an image, when the toner replenishment command is generated continuously by some prescribed number of times such as 10 times or 15 times, a desired image density it obtained, therefore, at the time of the next image formation, the toner replenishment command is stopped. On the other hand, when a toner concentration control means causes an abnormality, the toner replenishment command is not stopped, but generated, even if it reaches such a prescribed number of times. Accordingly, by monitoring the number of times by which the toner replenishment command is generated continuously, an abnormality of the toner concentration control means can be discriminated. In such a way, this abnormality contains all abnormalities by which the toner concentration cannot be controlled, therefore, it can cope with not only a reversible abnormality but also an irreversible abnormality. |
