| 摘要 |
PURPOSE:To make it possible to execute the concentration control satisfactorily even when the electric power supply is put to work, by simple constitution, by controlling the solenoid for replenishing a developer in accordance with the logical product of a relative output corresponding to the difference between the reference concentration and the developer concentration, and a signal of every copy cycle. CONSTITUTION:Resistance of the element 4 is varied in accordance with the developer concentration between the light emitting device 3 and the photodetector 4, and a relative output by the comparator 8, corresponding to lowering of the developer concentration based upon the difference to the set resistance corresponding to the reference concentration, is applied to the logical product circuit 20. On the other hand, to the above circuit 20 is applied a signal of every copy cycle from the copying paper out-switch 19, and the driving circuit 14 of the solenoid for replenishing the developer is controlled through the monostable multivibrator 24 which is triggered by the logical product output of the circuit 20. Accordingly, since the concentration is controlled only after the copy cycle has started, while the agitation of developer has finished at the initial stage of imput of pawer supply, therefore concentration control failure caused by apparent low concentration at the time of input of power supply is not performed. Resulting from the foregoing, concentration control of a developer is executed satisfactorily even when the power supply inputs, by simple constitution. |
