To prevent the surface potential of a photoreceptor from getting unstable because of the adhesion of toner or the like to a grid electrode in charging the surface of the photoreceptor by the discharge of a charging device including a discharge electrode and the grid electrode in an electrophotographic image forming apparatus.
The image forming apparatus 1 has an electrophotographic processing part 21 including a photoreceptor drum 23, an optical scanning unit to be irradiated with signal light 50, a developing roller 26a, a transfer roller 28a and a cleaning unit 29. The image forming apparatus 1 includes a grid surface potential detecting means 56 for detecting the surface potential of the grid electrode 54 of the charging device 24, and a surface potential control means for stably holding the surface potential of the photoreceptor 23 within a range suitable for forming the image over a long term by controlling the voltage applied to the grid electrode 54 according to the result of detection outputted from the grid surface potential detecting means 56.
KAWAMOTO HIROSHI
FUKUTO NAOKI
MASUDA JITSUO
Takeshi Sugiyama
Minetarou Hirose