Patent ID: 7634202

Claim:
An image forming apparatus, comprising: a plurality of image forming stations each including an electrostatic latent image carrier, a static eliminator that eliminates charges on the electrostatic latent image carrier, and a charging member that is arranged to face the electrostatic latent image carrier while defining a specified gap; a bias applicator that collectively applies charging bias voltages including alternating-current components to the charging members provided in collective bias image forming stations, the collective bias image forming stations being at least two of the plurality of image forming stations; a current sensor that collectively detects currents flowing in the charging members provided in the respective collective bias image forming stations; and a detector that detects an abnormal discharge in the gap between the electrostatic latent image carrier and the charging member based on a current detection result by the current sensor, wherein the detector selects one of the collective bias image forming stations as a selected image forming station, and determines presence or absence of the abnormal discharge in the gap between the electrostatic latent image carrier and the charging member in the selected image forming station based on the current detection result by the current sensor when the bias applicator applies the charging bias voltages to the charging members in the respective collective bias image forming stations while causing the static eliminator provided in the selected image forming station to operate and causing the static eliminators provided in the collective bias image forming stations other than the selected image forming station to stop operating.