Image forming apparatus and image forming method for forming color images by gray-level image forming technique

摘要

The present invention is aimed at carrying out high-precision and stable image formation using a gray-level image forming technique. In carrying out image formation by a gray-level electrophotographic process, the relationship between the layer thickness Tp of the photosensitive layer on the photosensitive member and the exposure diameter Db of a light beam emitted onto the photosensitive member is defined as 2Tp Db, so that the charge diffusion and electric field in the photosensitive layer on the photosensitive member can be small. The maximum exposure within the exposure diameter Db is set at a value that can sufficiently reduce the differential sensitivity of the photosensitive layer, where the exposure diameter Db of the light beam is the minimum diameter at 1/e² with respect to the peak value of the exposure distribution obtained by integrating the energy distribution of the light beam with the exposure time. In this manner, excellent gray-level image presentation can be obtained, and high-precision and stable image formation can be carried out by using a region of damping characteristics on the photosensitive member.