| 摘要 |
PURPOSE:To obtain a copy high in quality free from dot reproduction on an image part such as a ground part or a solid part and lack of information on a low density original part by inserting a dot screen with a half tone setting up dot density to 0.4-1.0 into an exposure optical path and forming an image through the dot screen with the half tone. CONSTITUTION:The dot screen is arranged in the optical path part set up on the original platen side and the color tone of the dot screen is set up to 0.4-1.0 original density value which is the density of an area where an N line indicating the relation between original density and image density obtained at the time of using no dot screen is almost lineearly changed. Consequently, dot erasing on the ground part can be attained only by increasing exposure slightly or increasing a developing bias voltage, so that an original part with low density such as a part written with a pencil can be prevented from the lack of information, the clearness of characters or lines on a copied image can be improved and a copy image excellent in quality free from dot reproduction on the ground part or the solid part can be obtained. |
