Image forming apparatus for forming an image to change the potential of a photoconductor

An image forming apparatus comprising:

• a photoconductor;
• a corona charger disposed to oppose a surface of the photoconductor and configured to charge the surface of the photoconductor;
• an exposure unit configured to expose the surface of the photoconductor that is charged by the corona charger to exposure so as to form an electrostatic latent image on the surface of the photoconductor;
• a developing unit configured to develop, with toner, the electrostatic latent image that is formed by the exposure unit so as to form a toner image on the surface of the photoconductor;
• a developing bias application unit configured to apply a developing bias obtained by superimposing a DC voltage and an AC voltage to the developing unit;
• a transfer unit configured to transfer the toner image that is formed on the photoconductor onto a recording medium;
• and
• an execution unit configured to execute a first mode and a second mode, the first mode being a mode in which an electrostatic latent image is formed by the exposure means on the surface of the photoconductor that is charged by the corona charger and a toner image that is formed on the surface of the photoconductor by the developing means is transferred onto a recording medium and is output, the second mode being a mode in which a toner image that is formed on the surface of the photoconductor by the developing unit substantially without forming, by the exposure unit, an electrostatic latent image on the surface of the photoconductor that is charged by the corona charger is transferred onto a recording medium and is output as a toner image,
• wherein the execution unit sets a frequency of an AC voltage of the developing bias in the second mode to a value larger than a frequency of an AC voltage of the developing bias in the first mode.