| 摘要 |
PURPOSE:To stabilize copying density by forming an electrostatic latent image having a white pattern on a photosensitive body after stabilizing the surface potential of the photosensitive body, developing it by a developing bias lower than a prescribed developing bias in a developing device, detecting the adhering toner quantity by a photodetector and automatically setting the voltage of a lamp so that the detection value may be within a predetermined extent. CONSTITUTION:The electrostatic latent image of the white pattern having the density near the surface density is formed on the photosensitive body 11 by an exposure device 13 after the surface potential of the photosensitive body 11 is stabilized, and it is developed by the developing bias lower than the prescribed developing bias in the developing device, and the adhering toner quantity is detected by the photodetector 30, and the device is provided with a lamp voltage setting means 31 for automatically setting the voltage of the lamp 15 so that the detection value may be within the predetermined extent. Thus, the lowering of toner Q/M (electrostatic chargeability) and the increase of toner replenishment can be prevented even in the case that the electrostatic charging holding capacity of the photosensitive body does not reach a desired value, and then, the copying density can be stabilized. |
