| 摘要 |
PURPOSE:To excellently control the concentration of toner in a developing device main body by setting a precise control reference value obtained by expecting the stabilized state of the electrostatic charge amount of carrier after the aging of a short time. CONSTITUTION:An electrostatic latent image formed on the surface of a photosensitive drum 21 is developed to a toner image. Immediately after developer including the toner and the carrier is set in the developing device main body 14, stirring rollers 15 and 16 are rotated before the developing and the toner is triboelectrified. At this time, the concentration of the toner which is lower than the concentration of the toner detected by a toner sensor 1 is set as the control reference value. The control reference value is set by expecting the stibilized state of the electrostatic charge amount of the carrier. When the concentration of the toner detected by the sensor 1 becomes lower than the control reference value thereafter, a toner replenishing roller 20 is driven and the toner in a toner hopper 13 is replenished to the main body 14. |
