| 摘要 |
PURPOSE:To reduce the quantity of data for correcting gradation by determining gradation correcting data corresponding to a specific parameter from grid and bias potentials, the surface potential of a photosensitive body, and the attenuation potential of the photosensitive body when an exposure is carried out with the maximum light quantity. CONSTITUTION:The grid potential VG of an electrifying charger 43 and the bias potential VB of a developing unit 45r are set so as to keep the maximum density of an image constant. On the other hand, the gradation properties are changed by a parameter showing the ratio of the differences between the VB and the V1, and between V0 and V1, that is, (VB-V1)/(V0-V1) and its inverse number, from the grid potential VG, the bias potential VB, the surface potential V0 of the photosensitive body 41, and the attenuation potential V1 of the photo sensitive body 41 when the exposure is carried out with the maximum light quantity, and the gradation is controlled with the use of the gradation correcting data corresponding to the parameter. Thus, the storage capacity of the gradation correcting data is reduced. |
