| 摘要 |
PURPOSE:To detect toner residual by discriminating the reduction of toner in a toner feeding means for detecting the toner density of a two-component developer stored in a developing unit and feeding toner less the a prescribed volume when the number of times of feeding by the toner feeding means exceeds a reference value. CONSTITUTION:The developing unit 7 executes development by using the two- component developer consisting of toner and carrier and the developer is carried to a sliding part with a photosensitive body 2 by a magnetic roller 21. A magnetic sensor 23 is fitted to the side wall of the developing unit 7 so that its detecting head 24 is exposed into the developing unit 7. The detected toner density is supplied to a microcomputer through an A/D conversion circuit. The computer compares the toner density with a set-up reference level and drives a solenoid in accordance with the compared result to feed the constant quantity of toner to the developing unit 7. The number of times of toner feeding is calculated, and when the calculated value exceeds a reference value, the reduction of toner in a hopper 25 less than the prescribed volume is discriminated. Thus, the toner residual can be precisely detected. |
