| 摘要 |
PROBLEM TO BE SOLVED: To prevent fogging and faulty density by properly changing the DC component of developing bias based on the using circumstances of a photoreceptor drum (film thickness of photoreceptor) and using environment (temperature and humidity). SOLUTION: By applying voltage on an electrifying device 17 arranged in contact with the surface of the photoreceptor drum 16 and detecting the value of a current flowing the drum 16 at this time by a detection means 30, the change of the film thickness of the drum 16 is detected. According to the detection signal, the DC component of the developing bias impressed on the developing roller 21 of a developing device 18 is changed by a controller 31 so as to reduce what is called fogging at the time of developing. Then, output density is made appropriate by changing the DC component of the developing bias by the controller 31 according to output from a temperature and humidity detection means 32. |
