| 摘要 |
PURPOSE:To obtain stable recorded images of high quality by measuring the surface potential of a photosensitive body in two different positions on both sides of a developing means to estimate the surface potential in the developing position and controlling the electrification potential so that this estimated surface potential of the photosensitive body in the developing position is a certain value. CONSTITUTION:An electrification potential control means 110 applies a control signal to a first electrifying means 101 before the start of printing, and the surface potential is measured by first and second potential measuring means 102 and 106, and the surface potential in the position of a first developing means 104 is estimated by two measured surface potentials. Similarly, the control signal is applied to first and second electrifying means 101 and 105, and the surface potential is measured by second and third potential measuring means 106 and 109, and the surface potential in the position of a second developing means 108 is estimated by two measured surface potentials. The electrification potential is controlled by an electrification potential control means 110 so that the surface potential in each developing position estimated in this manner coincides with a target surface potential. Thus, stable recorded image of high quality are obtained.
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