| 摘要 |
PURPOSE:To obtain a detector of simple constitution which detects the residue of a powdery developer while securing the flowability of the developer and allows reduction in the size of a developer storage housing by providing a movable electrode which differs in displacement quantity according to the amount of the developer in the housing. CONSTITUTION:When a magnet roller 3 rotates, a diaphragm 6 vibrates to put the movable electrode 4 in reciprocal oscillation. Then when the quantity of the developer 2 in the housing 1 is abundant, the electrode 4 receives the weight of the developer and vibrates against the resistance of the developer nearby a fixed electrode 7, so its amplitude also decreases. When the rest of the developer 2 decreases and the influ ence of its load is eliminated, on the other hand, the electrode 4 leaves the electrode 7 and vibrates while the resistance of the developer is small, so the amplitude increases. Further, the electrodes 4 and 7 constitute an oscillation circuit 9 equipped with an OP amplifier 8 and its oscillation frequency and oscillation level vary as the capacity between the electrodes 4 and 7 varies. The output signal of the circuit 9 is integrated by an integration circuit 10 and inputted to a comparator 1. When the input signal drops below a reference value, a developer supply display device 12 operates. |
