PURPOSE: To suppress accumulation of the residual potential remaining when copying is repetitively executed and to maintain good image quality by maintaining A>B when an electric field of the same polarity as an image forming polarity is defined as A and an electric field at the time of image formation as B.
CONSTITUTION: A latent image is formed by impressing the electric field of the same polarity as the image forming polarity on the surface of a hole transfer type photoreceptor formed with a protective layer (b) on a photoconductive layer, then impressing the electric field of the polarity reverse from the polarity at the time of image formation thereon to generate the surface potential necessary for image formation and subjecting the surface to image exposing. Here, A>B is obtd. when the electric field of the same polarity as the image forming polarity is defined as A and the electric field at the time of image formation as B. The electric field at the time of image formation refers to a value (electrostatic charge potential and the film thickness of the photosensitive layer) obtd. by dividing the electric field impressed at both ends of the photoreceptor just before the latent image formation by the film thickness of the photosensitive layer c including the protective layer (f). This electric field A is preferably 1.2×105 to 1.0×106(V/cm) and the electric field difference between the electric field A and the electric field B is 2×104 to 7.5×105(V/cm).
KOJIMA SHIGETO
IKUNO HIROSHI
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