| 摘要 |
PROBLEM TO BE SOLVED: To provide an offset printing machine which does not require an alkaline developer, then produces a high quality printed image whose image area and non-image area are sharply identifiable, and can use a master plate for printing repeatedly. SOLUTION: A plate cylinder 1 with a thin coat composed mainly of titanium oxide, zinc oxide or the like formed on the surface is entirely exposed to an active light by an active light emission part 2 to turn the surface hydrophilic. After that, an image is drawn in the heat mode by a heat-sensitive recording part 5. Consequently, a non-image area which is hydrophilic, to which the active light is emitted and an image area which is lipophilic and shows a drawn image, are formed on the plate cylinder 1. In addition, an ink and a moistening water are supplied from an ink/moistening water supply part 3 and are borne by the plate cylinder 1 to perform a printing operation. After its completion, a residual ink in the plate cylinder 1 is cleaned off by an ink cleaning part 4 and the whole surface of the plate cylinder 1 is exposed to the active light and is restored to a state before the drawing of an image in the heat mode. Thus it is possible to perform the printing operation through repeatedly using the plate cylinder 1. |
