| 摘要 |
PURPOSE:To prevent an image from fogging or image dropout by providing plural detecting means which detect the distribution quantity of a developer in the axial direction of a developer holding member and controlling the driving of a developer supply means and a developer conveying means according to the combination of detection signals. CONSTITUTION:An electromagnetic latent image formed on a latent image carrier 1 is developed by a developing device 2 which is arranged opposite. Developer volume detecting means 8 and 8 are provided inside both opposite side walls of a mixing part 5 and the developer conveying means 9 is provided below the means 8 and 8 in parallel to the developer holding member 3. An area B is a circulation area when the mixing ratio of magnetic particles and a nonmagnetic developer in a mixed body has a proper value and the developer distribution has not gradient; the output signals of the means 8 and 8 are both off and no nonmagnetic developer is supplied from a hopper part 6. When the volume of the mixed body decreases, the circulation area of the mixed body is the area A and the means 8 and 8 turn ON to put a nonmagnetic developer supply means 7 in operation. Further, when the distribution of the mixed body in the axial direction of the holding member varies, that is detected by the means 8 and 8 and the means 9 is put in operation. |
