| 摘要 |
PURPOSE:To precisely detect the rest of developer by arranging a reference electrode outside a developer room and arranging a signal electrode inside the developer room in such a manner that it stands face to face with a magnetic pole located on the upstream side in a rotationally moving direction of a developer holder rather than a magnetic pole opposite to a developer restricting member out of magnetic poles of a magnetism generating means. CONSTITUTION:During development, AC high voltage is applied to a developing sleeve 6, a doctor blade 7 and a blade stay 8 to generate induced voltage in a reference electrode 12 and a signal electrode 13 adjacent thereto, respectively, so that the rest of toner T in a toner room 3 is detected in accordance with a difference between voltages induced to both electrodes 12, 13. In this case, the reference electrode 12 is arranged outside the toner room 3 and the signal electrode 13 is so arranged that it may stand face to face with a magnetic pole N2 located on the upstream side in a rotationally moving direction of the developing sleeve 6 rather than a magnetic pole S1 opposite to the doctor blade 7 out of magnetic poles of a magnet 11 in the developing sleeve 6. It is thus possible to detect the rest of developer stably and accurately. |
