An image forming apparatus comprising:
- an intermediate transfer member configured to be a movable member to which toner images are transferred;
- a first image bearing member configured to come into contact with the intermediate transfer member, the first image bearing member having a photosensitive layer bearing a chromatic toner image of a first polarity;
- a second image bearing member configured to come into contact with the intermediate transfer member at a location downstream of the first image bearing member in a direction of travel of the intermediate transfer member, the second image bearing member having a photosensitive layer bearing a black toner image of the first polarity;
- a first transfer member configured to transfer a toner image from the first image bearing member to the intermediate transfer member at a first transfer portion;
- a second transfer member configured to transfer a toner image from the second image bearing member to the intermediate transfer member at a second transfer portion;
- a voltage applying member configured to apply a voltage to the first transfer member and the second transfer member;
- a first detector configured to detect an adjustment toner image of chromatic color by irradiating the intermediate transfer member with light, the first detector being disposed downstream of the second image bearing member in the direction of travel of the intermediate transfer member;
- a second detector configured to detect an adjustment toner image of black color by irradiating the second image bearing member with light;
- and
- an adjusting portion configured to adjust an image forming condition for the first image bearing member based on a result obtained using the first detector by detecting a first adjustment toner image transferred from the first image bearing member to the intermediate transfer member, and adjusting an image forming condition for the second image bearing member based on a result obtained using the second detector by detecting a second adjustment toner image formed on the second image bearing member,
- wherein the voltage applying member is controlled such that when the first adjustment toner image and the second adjustment toner image simultaneously pass through the second transfer portion in the direction of travel of the intermediate transfer member, a first voltage of the first polarity is applied to the second transfer member, the first voltage being a voltage that makes a potential difference between the second image bearing member and the intermediate transfer member less than a discharge start voltage.