| 摘要 |
<p>To form a high-resolution highly stable image by using an image forming technique including gray scale expression. On the assumption that the image is formed by an electrophotography process including gray scale expression, the relation between the thickness Tp of the photosensitive layer of a photosensitive element and the exposure diameter Db of a beam applied to the photosensitive element is predetermined to be 2Tp < Db, thereby reducing the charge diffusion and development field extension in the photosensitive layer of the photosensitive element. From the peak value of an exposing luminous power distribution which is defined by integrating the energy distribution of the beam on the photosensitive element with respect to the exposure time, a minimum diameter at 1/e2 is selected as the exposure diameter Db of the beam, and a maximum exposure luminous power within this exposure diameter Db is set at a value with which the differential sensitivity of the photosensitive layer is sufficiently lowered. With this constitution, the region of the attenuation characteristics of the photosensitive element which is good enough to obtain a high-resolution highly stable image can be used while the gray scale expression by a gray scale expressing means is realized.</p> |
