| 摘要 |
PURPOSE:To permit expansion of a region of a transparent conductive window member where exact developer concn. detection is possible so that the exact developer concn. detection can be executed with good responsiveness by impressing an electric field including an AC component to the transparent conductive window member. CONSTITUTION:An AC power supply AC 38 and a DC power supply DC 37 are connected in series to the transparent conductive window member 34 and the AC electric field superposed with the DC electric field is impressed by these two power supplies to the transparent conductive window member 34. The toner 22 sticking to the transparent conductive window member 34 is then removed by the rubbing of the napping part of the developer layer formed on the outside peripheral face of a developing sleeve 13 to the transparent conductive window member 34 by the magnetic pole of a magnet roller 14 and also by the oscillation of the toner itself generated between the transparent conductive window member 34 and the developing sleeve 13 by the impression of the electric field thereto. The width A of the developer concn. detection in the transparent conductive window member 34 is also greatly expanded. The detection of the developer concn. at the response speed capable of dealing with the variation in the developer concn. is, therefore, possible and is executable with high accuracy. |
