Image forming apparatus

An image forming apparatus comprising:

• an image carrier in which a photosensitive layer is formed on an outer circumferential surface of the image carrier;
• a charging part for electrically charging the outer circumferential surface of the image carrier to a specified surface potential;
• an exposure part for making the outer circumferential surface of the image carrier, which has been electrically charged by the charging part, exposed to light to form an electrostatic latent image with its charging level attenuated;
• a developing part for feeding toner to the electrostatic latent image on the image carrier to form a toner image, and moreover collecting the toner remaining on the outer circumferential surface of the image carrier;
• a belt placed so as to face the image carrier;
• a transfer part for transferring the toner image, which has been formed on the outer circumferential surface of the image carrier, onto an outer circumferential surface of the belt;
• a cleaning roller for removing and collecting deposits on the outer circumferential surface of the image carrier;
• a voltage application part for controlling electrical energization for the charging part, the developing part, the transfer part, and the cleaning roller;
• a concentration detection part for detecting a toner concentration of the toner image transferred onto the outer circumferential surface of the belt;
• and
• a controller for controlling the image carrier, the charging part, the developing part, the transfer part, the cleaning roller, and the voltage application part, wherein
• the controller:
• makes a reference image, which is the toner image, formed on the outer circumferential surface of the image carrier and transferred onto the outer circumferential surface of the belt;
• makes uncollected toner of the reference image, which is part of after-transfer remaining toner of the reference image that has missed being collected by the cleaning roller and the developing part and remains even after one-round rotation of the image carrier, transferred to the outer circumferential surface of the belt;
• estimates an uncollected toner quantity on a basis of the toner concentration of the uncollected toner detected by the concentration detection part, and moreover measures a collectable toner quantity corresponding to an applied voltage of the cleaning roller on a basis of the uncollected toner quantity;
• and
• adjusts the applied voltage of the cleaning roller so that the collectable toner quantity becomes equal to or larger than a maximum value of the after-transfer remaining toner quantity while the applied voltage of the cleaning roller becomes equal to or lower than a maximum applicable voltage.