| 摘要 |
PURPOSE:To obtain automatically constant picture density by detecting a current generated at the transfer of toner from a developing roll to a photoreceptor by a current detecting circuit and controlling the rotation of a driving motor to supply toner corresponding to the consumed volume of toner from a toner supplying auger. CONSTITUTION:When a developer is contacted with the surface of a photoreceptor forming an electrostatic latent image on its surface, toner in the developer corresponding to the charge level of the electrostatic latent image is transferred to the side of the photoreceptor 1, electric charge corresponding to the charge of the toner grains disappears from the surface of a developing roll 10 and the current flowing from a developing bias power supply 15 into the developing roll 10 to fill up the disappeared charge is detected by a current detecting circuit 17. The detected value is integrated by an integrator 6 and converted by an A/D converter 19 and the converted digital signal is inputted to the driving motor 13a to rotate the toner feeding auger 13 and to feed the toner in a toner bottle 12 to the housing 4a of a developing device 4a. Since the toner contents in the developer can be maintained always at a constant level, the density of a copied picture can be fixed. |
