| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect toner amount by restraining the dispersion of detected voltage caused by the dispersion of an integration circuit. SOLUTION: In the external circuit of an electrostatic capacity detecting device 37, an AC current flowing to an antenna electrode 34 from a developing sleeve 23 and an AC current flowing to a reference capacitor 607 therefrom are respectively converted into half-wave currents in different directions, and two currents are added and then inputted in one integration circuit 620 so as to be turned into DC voltage. The integration circuit causes the dispersion of the constant of a resistance and the capacitor used in the circuit and the dispersion of characteristic caused by stray capacity or a leak current occurring in the case of constituting the integration circuit on a substrate, and such failure is eliminated by constituting the integration circuit of the device 37 of one circuit. |
