| 摘要 |
PURPOSE:To always decide exactly the quantity of replenishment of a toner irrespective of the number of sheets of copying, by executing the control of a toner replenishment time in the course of operation of a developing device, for instance, executing the charging of a time constant capacitor in a prescribed time in the course of operation of the developing device. CONSTITUTION:Reference voltage from a standard toner density passive reflector and voltage signal (b) corresponding to the toner concentration on a sleeve are supplied to an amplifier Q1 and are amplified by one stage, and are supplied to an impedance converting transistor (TR) Q3. A comparator Q2 generates a comparison output (e) only when both end voltage C of a capacitor C1 is larger than the signal voltage (b) corresponding to the toner concentration on the sleeve. Since standard toner density in the passive reflector is already known, a charging time of a passive reflector signal in the capacitor C1 corresponding to said density can also be set to a prescribed time in advance. A CPU 11 waits for completion of charging of the capacitor C1 and ends a charging time of a charging and discharging signal (f). As a result, the quantity of replenishment of a toner can be controlled at all times irrespective of the number of sheets of copying. |
