| 摘要 |
PURPOSE:To enable only image areas of density up to an optional intermediate density to be reproduced, by applying bias voltage to a controlling grating, and transferring an image with a transferring device reverse in polarity to charge of a latent image. CONSTITUTION:Discharge electrode 4 of corona discharger 3 preceding transfer shielded with discharger shield 5 is connected to high voltage source 8 reverse in polarity to toner. Controlling grating 6 with tungsten wires stretched e.g., at intervals of 0.5-2mm. is provided in the shield opening on the side of photoreceptor 1. A voltage between the potential of the light area of a photosensitive plate and that of the dark area is applied to grating 6 from bias voltage source 7. An electric field for accelerating corona ions and an electric field for restricting corona ions are formed between the surface potential of photoreceptor 1 and grating 6 using discharger 3 in such a structure, in order to convert the polarity of part of the toner on photoreceptor 1 into the reverse polarity and to reproduce part of the image selectively. |
