| 摘要 |
PURPOSE:To detect adhesion of excessive toner on the drum due to the deterioration of developer by providing an optical sensor at a place outside of a charged area and inside of a developed area of a photosensitive drum. CONSTITUTION:The photosensitive drum 5 is charged in a width (b) and developed in the wider width (c). Accordingly, the intermediate part is not charged, and as a rule, the toner does not adhere. However, when the developer is deteriorated, the toner begins to adhere. Accordingly, contamination of the toner can be detected by providing a sensor in the part and observing a reflection factor of the drum surface. In case of a system in which whole circumference of the photosensitive drum 5 is not charged, and the operation of the charger is stopped when charging is made on the length of transfer paper, in measuring in the direction of rotation of the drum, the sensor can be provided at any position regardless of axial width of the drum. In such a case, the sensor is operated when charge area on the drum surface completes its passing. |
