Image forming apparatus with control of charging, exposure and

Abstract

An exposure step input circuit inputs a desired brightness of a printing image as one of a plurality of exposure steps and a lamp application voltage adjusting unit allows the application voltage of an exposure lamp to, on the bright side of the exposure steps, be increased with a smaller predetermined slope than a dark side each time the exposure step is switched in the bright direction. At this time, a shortage of an exposure is compensated for by lowering a surface potential on a photosensitive drum through the decreasing of a charge current by a charger or raising a developing bias voltage of a developing unit. An image forming apparatus thus provided can obtain a better image at all times by, even on the bright side of the exposure steps in the adjustment of an exposure amount, preventing a lowering in density of an image, deposition of carriers, and other disadvantages.