| 摘要 |
PURPOSE:To make possible the easy detection of potential with a simple device and good accuracy by developing the surface potential formed under predetermined conditions on a latent image carrying body to a sensible image by the developing bias potential predetermined by a developing device and detecting the toner deposition thereof. CONSTITUTION:A bias changeover control circuit 32 changes over the developing bias potential of a bias power source 30 to +950V at the timing when the next uniform electrostatic charge part on a photosensitive drum 2 passes the developing device 4. A density detecting circuit 27 operates at the timing when the uniform electrostatic charge part passes the density detecting position of density detectors 25, 26. The circuit 32 decreases successively the developing bias potential of the power source 30 at the respective timings when the respective uniform electrostatic charge parts on the drum 2 pass the developing part 4 in the same manner thereafter. The circuit 27 operates at the timings when said uniform electrostatic charge parts pass the density detecting positions of the density detectors 25, 26. The sticking of a toner to the uniform electrostatic charge parts on the drum 2 by the device 4 is started from the point of the time when the potential thereof is made approximately the same as the developing bias potential. |
