| 摘要 |
PURPOSE:To improve the collection efficiency of impurities by directing a line of magnetic force which has been generated from a magnet, to a magnetic material which has been provided on the lower part of a developing sleeve as low as possible, and weakening a restraint of the impurities held between magnetic brushes. CONSTITUTION:When a developing operation is being executed, a developer carried on a developing sleeve 7 is superposed on each other lamellately and becomes dense along a line of magnetic force between magnetic poles of each opposite polarity, and impurities are held in the developer. However, when it reaches an opening part 4a opposed to a magnetic pole N2, it rises in the radial direction extending over a wide range along the line of magnetic force directed to a mesh 21, the line of magnetic force in the vicinity of the magnetic pole N2 and a magnetic brush become sparse, and impurities such as an electrification failure toner held in the magnetic brush, paper powder, dust, etc., lose its restraint, and drop down to a collecting container 22 through the opening part 4a and the mesh 21 by the gravity and the centrifugal force. In this way, the impurities are separated and collected satisfactorily, the collecting container 22 is taken out at every prescribed copy sheet number, and dumped. |
