Patent ID: 7633515

Claim:
An exposure apparatus comprising: a light source for emitting a light beam with a light quantity corresponding to a current amount supplied; a rotating polygon mirror with a plurality of reflection planes, said rotating polygon mirror rotating in a manner that the light beam emitted from said light source and reflected off a reflection plane scans on a photosensitive body; beam magnifying means for expanding the light beam emitted from said light source in a manner that the light beam is irradiated onto said rotating polygon mirror with a beam width exceeding a width of each reflection plane of said rotating polygon mirror in a scanning direction; correction current profile memory means for storing a plurality of correction current profiles that will provide the scanning direction with a nearly fixed light quantity of the light beam irradiated onto said photosensitive body; setting means for selecting from a plurality of levels a target light quantity of the light beam irradiated onto the photosensitive body, and for setting the target light quantity selected; and current supplying means for selecting one of the plurality of correction current profiles stored in said correction current profile memory means in response to the target light quantity set by said setting means, and for supplying said light source with a current passing through correction based on the correction current profile selected, wherein said current supplying means comprises; a D/A converter; designating means for designating a transfer start address, a number of transfer data and transfer clock of the data in said correction current profile memory means in response to the target light quantity set by said setting means; data supplying means for reading data in said correction current profile memory means in response to the information designated by said designating means, and for transferring the data to said D/A converter; and a constant current circuit for converting the output voltage of said D/A converter, which is obtained in response to the data transferred from said data supplying means, to a constant current, and for supplying the constant current to said light source.