| 摘要 |
PURPOSE:To facilitate the processing with a larger output by providing a photoelectric detector at a detection window provided on a housing corresponding to a developer stirring blade with cleaning magnet to turn OFF the detecting operation during the cleaning with a magnet. CONSTITUTION:A developer 14 is made feedable to a photosensitive body 12 with a developing roll 13 provided in a housing 11 and a magnet 16 is mounted on a stirring blade 15 provided in the housing 11 side by side with the roll 13 to allow the cleaning of a toner concentration detecting window 17 provided on the side of the housing 11 as opposed to the blade 15 with the magnet 16. In addition, a photoelectric detector 18 comprising a light emitting body 181 and a light receiving body 182 is provided at the window 17 to detect variation in the reflectance of light irradiated on the developer 14 through the window 17 from the light emitting body 181 with the light receiving body 182. Here, the detector 18 is turned OFF during the cleaning of the window 17 with the magnetic brush action of the magnet 16 accompanied by the rotation of the blade 15 and the output is taken out during the period other than this. |
