| 摘要 |
PURPOSE:To supply the prescribed amount of toner by installing plural induced voltage generating means at a position with different heights in a toner containing part, detecting a toner amount by logically judging an induced voltage difference and the induced voltage of the slave generating means to replenish the toner. CONSTITUTION:Detecting conductors 5 and 6 as an induced voltage generating means are arranged in a developing device main body 1 containing the toner 2 by facing a developing roller 3. Their induced voltages are rectified by rectifier circuits 12 and 13, and supplied to a comparator circuit 15 through a differentiation circuit 14. And a voltage rectifying the induced voltage of the slave conductor 5 is supplied to the comparator circuit 17. An output compared with a comparison voltage Vth1 in the circuit 15 and an output compared with a comparison voltage Vth2 in the circuit 17 are inputted to a motor control circuit 16 through an OR circuit 18. Thus a state where toner is less is securely detected to appropriately supply the prescribed amount of toner. |
