Patent ID: 7202675

Claim:
A toner current measuring device comprising: a toner deposit capacitor having opposing electrodes, charged toner to be deposited on one of the electrodes; a reference capacitor having a variable capacitance, to be configured by a user adjustment with a capacitance substantially equal to a capacitance of the toner deposit capacitor having charged toner deposited on the one electrode; a power supply unit operable to supply power in parallel to the toner deposit capacitor and the reference capacitor; and a measuring unit operable, when the power supply unit applies a voltage to both capacitors which causes a transfer, between the opposing electrodes, of the charged toner deposited on the one electrode, to measure a difference between a current flowing in the toner deposit capacitor and a current flowing in the reference capacitor, the difference being measured as a toner current generated by the transfer of the charged toner.