| 摘要 |
PURPOSE:To prevent scattering of a toner by detecting the situation of toner sticking to the non-image forming part of the image area on the surface of a drum,, which causes toner scattering, by a reflex optical sensor to raise a predictive alarm. CONSTITUTION:If the light reflectivity is reduced by toner sticking to the non- image forming part on the drum and the quantity of incident light on a photo transistor TR 29 of a toner scattering detector is smaller than a prescribed value, the TR 29 is turned off. As the result, a collector potential V1 is raised and the output of a comparator 32 goes to the high level. Thus, toner sticking to the non-image forming part on the drum is detected. Since the toner is more replenished according as the toner is gradually accumulated on the non-image forming part after the start of sticking and the toner consumption is increased, toner scattering is caused by the occurrence of electrification defect of the toner or the like. Consequently, toner sticking to the non-image forming part on the drum is detected to quickly detect toner scattering in the foreboding stage. |
