| 摘要 |
PURPOSE:To shorten a time until the output of a toner concentration sensor is stabilized, to set a reference value required for adjusting toner concentration in a short time and to shorten much time specially with respect to a color copying machine provided with plural developing devices by quickly and uniformly mixing toner and carrier. CONSTITUTION:When developer is exchanged, respective rollers 28-31 in the developing device are rotated at the speed revolution which is about 1.2-1.3 times as high as at an ordinary developing action time and the carrier and the toner in the developer 40 are uniformly mixed. Then, the time that the output of the toner concentration sensor 35 is stabilized waited for and the fixed output of the sensor 35 is stored the reference value. On and after, the replenishing quantity of the toner is controlled by comparing the measured toner concentration of the developer 40 with the reference value and the toner concentration is held to be fixed. |
