Patent ID: 7937032

Claim:
An image forming apparatus for adjusting the position at which a toner image is formed on a printing material, based upon amount of light reflected by a toner image that has been formed on an image carrier, said apparatus comprising: a light-emitting unit which emits light that irradiates the image carrier; a detecting unit which detects amount of substrate-light reflected from a substrate of the image carrier; a determining unit which determines whether the difference between the amount of substrate-light detected at a first point in time and the amount of substrate-light detected at a second point in time later than the first point in time is greater than a predetermined threshold value; a light-power control unit which increases the amount of light in said light-emitting unit if the difference is greater than the predetermined threshold value; and a storage unit which stores an amount of substrate-light, which has been detected at a starting point in time of a print job introduced to said image forming apparatus or at a boot-up point in time of said image forming apparatus, as the amount of substrate-light at the first point in time.