Image forming apparatus

An image forming apparatus comprising:

• a plurality of toner image forming devices each of which including:
• a latent image bearer to bear a latent image;
• a developing device to develop the latent image with developer including toner;
• and
• a lubricant applicator to apply lubricant onto a surface of the latent image bearer,
• the plurality of toner image forming devices including:
• a black image forming device to use black toner and a developing bias without an AC component;
• and
• a color image forming device to use color toner other than the black toner and a developing voltage including an AC component,
• wherein an amount of the lubricant applied by the lubricant applicator onto the latent image bearer per centimeter in an axial direction of the latent image bearer is equal to or greater than 0.845 mg for a running distance of 1.0 kilometer of the latent image bearer, and
• wherein a difference between a largest value and a smallest value of the developing voltage including the AC component is in a range of 200 V to 400 V, an average value of the developing voltage being less than 0 V, and the largest value of the developing voltage being closer to 0 V than the smallest value of the developing voltage.