Patent ID: 8175505

Claim:
An image forming apparatus which forms image on a print medium by using a plurality of color toners, said image forming apparatus comprising: an image carrier; a plurality of image forming units configured to form toner images on said image carrier, wherein each of said plurality of image forming units forms different color toner image on said image carrier; a pattern formation unit configured to cause each of said plurality of image forming units to form a toner pattern on said image carrier; a detection unit configured to (i) include a light-emitting portion for emitting light to said image carrier and a light-receiving portion for receiving reflected light of the light emitted from the light-emitting portion, and (ii) detect a registration error between the different color toner images formed by each of said plurality of image forming units based on a light receiving result of the light-receiving portion; a light amount control unit configured to control amount of light to be emitted from the light-emitting portion based on amount of light reflected from the toner pattern and amount of light reflected from said image carrier, in a case where the detection unit detects the registration error; and a correction unit configured to correct the registration error detected by said detection unit.