| 摘要 |
PURPOSE:To take many copies of an image of stable contrast, by controlling light irradiation conditions and a bias voltage in development on the basis of a comparison value between a reference electrostatic contrast and an electrostatic contrast measured in every copying. CONSTITUTION:Unexposed part potential VD and exposed part potential VL of a photoreceptor are measured to calculate reference electrostatic contrast VC. Next, unexposed part potential VD' and exposed part potential VL' of an electrostaic latent image formed on the photoreceptor are measured to calculate electrostatic contrast VC' and when VC' os lower than VC, the entire surface of the photoreceptor is exposed uniformly with the quantity of light adjusted according to the difference. When VC' is within a prescribed range, whether the deviation of VC' from VC and development bias voltage VG set for development are out of phase and have nearly equal values or not is discriminated; when not, VG is adjusted and when so, development, transfer and copying processes are performed. Then, whether the copying is continued after the transfer is discriminated; when so, control process of VD' and VL' is repeated and when not, destaticization, cleaning, etc., are performed. |
