| 摘要 |
PURPOSE:To measure initial electrification with high resolution and to obtain a stable image with high image quality by providing a conductive probe measuring an initial electrification state, a dummy electrode and a surface electrometer measuring the potential of the dummy electrode. CONSTITUTION:A surface potential measuring device having probes 171-173, the dummy electrode 18 to which the probes 171-173 are successively, electrically connected and the surface electrometer 20 measuring the potential of the dummy electrode 18 is provided. At this time, the initial electrification of a photosensitive drum 11 can be measured with the high resolution by the surface potential measuring device, to obtain the stable image with the high image quality. In other words, the probes 171-173 are arrayed in the axial direction of the photosensitive drum 11, so that positional accuracy for measurement with respect to the photosensitive drum 11 is easily kept and miniaturization is attained. Moreover, plural probes 171-173 are selectively connected to one dummy electrode 18, to reduce the required number of the dummy electrodes. Thus, the device saved in space is obtained. |
