Image forming apparatus including first detection sensor and second detection sensor for detecting density detection pattern

An image forming apparatus comprising:

• an image carrier driven to rotate;
• a formation unit configured to form a first detection pattern for density detection on the image carrier for each color used in image formation, the first detection pattern including a chromatic color first detection pattern and an achromatic color first detection pattern;
• and
• a first sensor and a second sensor configured to detect the first detection pattern formed on the image carrier, the first detection pattern moving in a movement direction of a surface of the image carrier as the image carrier rotates,
• wherein the formation unit is further configured to form a second detection pattern for misregistration detection on the image carrier,
• the first sensor is further configured to detect the chromatic color first detection pattern and the second detection pattern,
• the second sensor is further configured to detect the achromatic first detection pattern and the second detection pattern, and
• the first detection pattern and the second detection pattern are formed such that the second sensor detects the achromatic color first detection pattern and the second detection pattern at the same time the first sensor detects the chromatic color first detection pattern.