US Patent 7692814 Image forming apparatus

Disclosed is the prevention of the occurrence of uneven image density, as well as the image degradation caused by inhibiting the continuity of image density, produced by the photoreceptor in which uneven electrification exists, and additionally uneven sensitivity coexists, without enlargement of the apparatus as well as increase in the cost. To the exposure amount obtained by the approximate linear transformation of the pixel gradation in each segment multi-divided in the surface of the photoreceptor drum 1, in all the pixel gradation including 0 level, exposing source 2 is controlled to expose with the amount of exposure, offset with only the offset exposure amount Ea which corresponds to the difference between the initial electric potential and the reference initial electric potential V0 of the segment. The exposure amount adjustment of the offset exposure amount Ea is conducted by offsetting the exposure time in each pixel.