| 摘要 |
PURPOSE:To detect the deterioration of a developer, by operating the density of a document on the basis of a picture signal, and comparing it with a reference value set previously. CONSTITUTION:A comparison portion 534 of a toner deterioration detecting means 53 compares the average density operated at an operation portion 532 with a reference value set previously, and decides if a toner has deteriorated or not. That is, the less the average density is, the less the development counter inside toner is, and it follows that the toner has stayed in the development counter, and its stirring time has become long, and the toner has deteriorated. And, when it is decided at the portion 534 that the toner in the development counter has deteriorated, the detecting means 53 outputs a deterioration signal to a toner deterioration preventing means 54, and toner deterioration is prevented. |
