Patent ID: 9261847
Filing Date: 2016-02-16
CPC Classification: G03G

Claim Text:
1. An image forming apparatus comprising: photoconductors configured to carry electrostatic latent images; electrifiers disposed in contact with or adjacent to the respective photoconductors and configured to uniformly electrify surfaces of the photoconductors; a power source configured to apply an electrifying voltage to the electrifiers, the electrifying voltage having an AC voltage superposed on a DC voltage; a current measurer configured to measure an alternating current caused to flow by application of an AC voltage by the power source; a controller configured to calculate a discharge starting voltage, which is a peak-to-peak voltage of the AC voltage at which discharge between the photoconductor and the electrifier is started; and environment detectors configured to detect an environment inside of the apparatus, wherein the controller is configured to operate the current measurer at each predetermined timing to acquire the discharge starting voltage, the controller being configured to, when acquiring the discharge starting voltage, change the peak-to-peak voltage of the AC voltage applied by the power source in at least two stages at pre-discharge voltage lower than the discharge starting voltage and at post-discharge voltage higher than the discharge starting voltage, the current measurer being configured to measure alternating current at two or more measurement points of each of the pre-discharge voltage and the post-discharge voltage, the controller being configured to calculate a voltage value at an intersection of a first line and a second line, the first line being acquired from a relationship between a peak-to-peak voltage of an AC voltage and an alternating current at two or more measurement points of the pre-discharge voltage, the second line being acquired from a relationship between a peak-to-peak voltage of an AC voltage and an alternating current at two or more measurement points of the post-discharge voltage, the controller being configured to, after acquiring the discharge starting voltage, calculate an environment-correction discharge starting voltage by correcting the discharge starting voltage based on the environment inside of the apparatus detected by the environment detectors, the controller being configured to set an electrification voltage based on the environment-correction discharge starting voltage, the electrification voltage being a peak-to-peak voltage of the AC voltage applied by the power source in image formation.