Image forming apparatus capable of simplifying control circuit

An image forming apparatus comprising:

• a plurality of image forming portions, each having
• an image-carrying member with a photosensitive layer formed on a surface thereof;
• a charging device configured to charge the surface of the image-carrying member;
• and
• a developing device configured to develop an electrostatic latent image formed on the image-carrying member into a toner image using a developing-agent-carrying member carrying a developing agent including a toner;
• the plurality of image forming portions configured to perform image formation using the toners of a plurality of colors with different developability;
• an exposure device configured to expose the surface of the image-carrying member charged by the charging device to form the electrostatic latent image in which charging is attenuated;
• an image density sensor configured to detect density of the toner image formed by the image forming portion;
• a developing voltage supply mechanism configured to apply a developing voltage to the developing-agent-carrying member;
• and
• a control portion configured to control the developing voltage supply mechanism and the exposure device;
• wherein
• the control portion,
• by the image density sensor detecting density of reference images for image density correction formed by a plurality of the image forming portions and adjusting the developing voltage and an exposure amount of the exposure device based on the detection result, is capable of executing image density correction to adjust image density in the plurality of image forming portions;
• the control portion,
• based on the density of the reference images detected by the image density sensor, sets the developing voltages in common such that the density of the reference images is equal to or higher than a target density in all of the two or more image forming portions selected from the plurality of image forming portions;
• and,
• by adjusting an adhesion area ratio of the toner for the image forming portions of two or more selected image forming portions in which the densities of the reference images exceed the target density when a common developing voltage is set, adjusts the densities of the reference images to the target density.