| 摘要 |
PURPOSE:To maintain the stability of toner concentration by controlling toner supplementation on the basis of the counted value of black data of an image signal, i.e. substantial toner consumption. CONSTITUTION:A black part counter 26 counts data on image parts of an output image that is contained in the image signal PB from an image signal processing circuit 25, and outputs a count-up signal CN when attaining to a preset value. A toner concn. detecting circuit 27 outputs a toner concn. signal ST according to the toner concn. in a developing device 4. A sequence control circuit 28 performs on-off control over a toner supplement clutch 29 on the basis of said count-up signal CN and toner concn. signal ST through a circuit which serves as a toner supplementing control means and controls the whole of the electrophotographic device to control the supplementation of toner 8 from a toner tank 6 to the developing device 4. |
