Image forming apparatus

An image forming apparatus capable of performing an image forming operation for forming an image on a sheet, the image forming apparatus comprising:

• an image carrier including a surface that is rotated to allow an electrostatic latent image to be formed and carries a toner image in which the electrostatic latent image is actualized by toner;
• a charging device charging the image carrier to a specific charging potential;
• an exposure device that is disposed on a downstream side in a rotation direction of the image carrier with respect to the charging device, and forms the electrostatic latent image by exposing a surface of the image carrier charged to the charging potential in accordance with specific image information;
• a developing device that is disposed to face the image carrier in a specific developing nip section on the downstream side in the rotation direction with respect to the exposure device, the developing device including a developing roller includes a peripheral surface rotated and carrying a developer including toner and carrier, and forms the toner image by supplying toner to the image carrier;
• a transferer that transfers the toner image carried on the image carrier to a sheet;
• a developing bias applicator capable of applying a developing bias in which an alternating current voltage is superimposed on a direct current voltage to the developing roller;
• a current detector capable of detecting a direct current component of a developing current flowing between the developing roller and the developing bias applicator;
• a density detector capable of detecting a density of the toner image;
• and
• a bias condition determiner that executes a bias condition determination mode for determining a reference voltage that is a reference for each of an inter-peak voltage of the alternating current voltage of the developing bias applied to the developing roller in the image forming operation and the direct current voltage, on a basis of the direct current component of the developing current detected by the current detector or a density of a toner image for measurement that is detected by the density detector when the developing bias is applied to the developing roller corresponding to a specific latent image for measurement that is formed on the image carrier, to develop, with toner, the latent image for measurement into the toner image for measurement,
• wherein the bias condition determiner can execute, as the bias condition determination mode, each of:
• a direct current voltage determination mode for determining a reference direct current voltage that is a reference for the direct current voltage of the developing bias applied to the developing roller in the image forming operation, on a basis of the density of the toner image for measurement, detected by the density detector;
• and
• an inter-peak voltage determination mode for determining a reference inter-peak voltage that is a reference for the inter-peak voltage of the alternating current voltage of the developing bias applied to the developing roller in the image forming operation, on a basis of the direct current component of the developing current detected by the current detector when the developing bias is applied to the developing roller to develop, with toner, the latent image for measurement into the toner image for measurement,
• wherein the bias condition determiner determines whether or not to execute the inter-peak voltage determination mode in accordance with the reference direct current voltage determined in the direct current voltage determination mode.