| 摘要 |
PURPOSE: To prevent toner from sticking to a photoreceptor by setting potential at the time of detecting an index so that developing bias potential may be lower than the surface potential of an area where the photodetector is irradiated with the light of a detector. CONSTITUTION: The index 8 for detecting the rotating position of the photoreceptor 61 is provided at a position opposed to a synchronizing sensor 7 in the shaft direction of the photoreceptor 61. The sensor 7 detects the index 8 and obtains the rotating position of the photoreceptor 61. When the timing of detecting the rotating position of the photoreceptor 61 is attained, an electrifier 62 is turned on at electrification control potential (grid potential). After the lapse of the prescribed fixed time, the electrification control potential is made lower than the oridnary control potential only while the photoreceptor 61 is rotated once. The sensor 7 is controlled after it is delayed with reference to the electrifier 62 by a fixed time equivalent to a potential difference. Then, the sensor 7 is turned on after it is delayed by the fixed time from timing when the electrification control potential of the electrifier 62 is lowered, and thereafter it is turned off when the photoreceptor 61 is rotated once. |
