| 摘要 |
PURPOSE:To obtain an electrostatic image having a large contrast with a small image exposure value, by giving an even exposure to the entire surface of a photoreceptor after the image exposure. CONSTITUTION:An electrophotographic receptor is evenly charged with electricity by a charger 3 (with surface potential V1), and an image exposure A is carried out with an exposure value E3. The bright part has the attenuation of brightness (with surface potential V3) based on a characteristic curve (a); while the dark part has the attenuation of darkeness (with surface potential V2) based on a characteristic curve (b) respectively. Then the surface potential of the bright part is further lowered with an even exposure B. The dark part also has the attenuation of brightness according to a characteristic curve (a'), but the potential V2 has virtually no reduction since the attenuation of brightness of the photoreceptor is very small while the exposure value is small. The contrast of an electrostatic image set at V2-V3 during the exposure of image is increased by the even exposure of E4-E3. As a result, the same contrast as conventional is attained with a small image exposure value. |
