| 摘要 |
PURPOSE:To obtain image quality smoothed even in the case of making an offset printing plate using the recording medium of an image consisting of dots as a original by exposing a photosensitive body at a position selected between focused and nonfocused positions. CONSTITUTION:A zinc oxide photosensitive sheet 1 is uniformly charged on the surface with a charger 5, and then, exposed at the position of an exposing plane B by illuminating an original face A, and projecting the reflected light from the original through a reflective mirror 3 and an image focusing lens 4 on the sheet 1, and an electrostatic latent image is formed, while the sheet is conveyed in the direction of arrow (a). This image is developed with a wet type developing device 6, and further sent in the direction of arrow (b), and the sheet 1 is subjected to etching treatment to form an offset printing original plate. In this exposure process, a dot image is smoothed by shifting the face A to a position A', the position C of the lens 4 to that C', or the plane B to a position B', or any 2 of them. |
