Patent ID: 7471906

Claim:
An image forming apparatus comprising: a photoconductor that is rotationally driven and has a photoconductive thin film formed on the surface thereof; an electrifying member that is disposed in contact with or in proximity to the photoconductor and electrifies the photoconductive thin film; a high voltage applying unit that applies to the electrifying member a high voltage achieved by superposing a DC component of a constant voltage generated from a DC generator on an AC component of a constant current generated from an AC generator; a DC current measuring unit that measures a DC current value flowing from the electrifying member to the photoconductor when the photoconductor is electrified; and a controller that integrates the DC current value measured by the DC current measuring unit for a time during which the DC component is applied to the photoconductor, calculating an electrostatic charge quantity of a DC current flowing into an electrostatic capacitance unit constituting the AC generator and subtracting the electrostatic charge quantity from the integration result to calculate the electrified charge quantity corresponding to the film thickness of the photoconductive thin film.