| 摘要 |
PURPOSE:To detect and control the density of a developer within an optimum range, by controlling the output of an electric circuit on the basis of the detection signal of a density detector. CONSTITUTION:A magnetic brush type developing roll 19 is provided facing a latent image holding means 33 and consists of a developing sleeve 19a incorporating a developing magnet driven to rotate; and means for supplying the developer 22 with higher than specific density onto the circumferential surface of the roll 19 and an insulating roll 20 formed by forming a dielectric layer 20b on a dielectric 20a are provided closely in parallel. Then, the electric circuit 26 applies an adequate DC voltage between the developing roll 19 and insulating roll 20 to dislocate an excessive developer 22 sticking to the developing roll 19 onto the insulating roll 20, and a density detector 29 is arranged on the circumferential surface of the developing roll 19. The output of the electric circuit 26 is controlled by the detection signal of the density detector 29. |
