| 摘要 |
PURPOSE:To directly detect a toner amount used during developing so as to effectively control toner concentration in developer, to disuse a toner concentration sensor and to reduce cost. CONSTITUTION:In the developing unit of a copying machine which develops an electrostatic latent image formed on the surface of a photosensitive body 4 by the magnetic brush 30 of the developer formed on the surface of a developing sleeve 29b; a current flowing to a conductive plate 31 from the sleeve 29b in the case that the magnetic brush 30 abuts on the conductive plate 31 provided at a position on which the leading edge of the brush 30, which finishes rubbing the photosensitive body 4, abuts on is detected by a current detector 32; and the consumption of the toner at the time of developing is calculated based on the change of the detected current value by a CPU 15. |
