| 摘要 |
PURPOSE:To prevent excessive contamination by providing an electret having a polarity opposite to that of toner in a supporting structural body and providing a sensor for detecting the contamination of the electret by the toner near the electret. CONSTITUTION:The electret E having the polarity reverse to that of the toner and being an electrostatic charging body for semipermanently generating an electric field on an external part and having an electric polarization characteristic is provided in the supporting structural body of an image forming device provided with an image outputting means including a photosensitive drum 26 which is turnably supported in the supporting structural body. The scattering toner is attracted and caught by the surface of the electret. The toner which is attracted once is semipermanently caught by the electret and never scatters again. And the sensor 112 for detecting the contamination by the toner is provided near the electret. An optical sensor, or a potential sensor, etc., are used as the sensor. When the quantity of the adhering toner reaches a prescribed quantity in the case of detecting the contamination of the electret by the toner by the sensor, a well-known warning means informs of the effect. |
