| 摘要 |
PROBLEM TO BE SOLVED: To conduct a lithographic printing with a digital dealing without developing by executing by an ink jet type for discharging an oily ink by using an electrostatic field to form a plate printing image. SOLUTION: A plate material 9 is mounted at a plate cylinder 11. Data from a magnetic disk unit is given to an image data arithmetic controller 21, a color separation is conducted according to the data, and a halftone dot areal rate is calculated. The controller 21 rotates the cylinder 11, moves an ink jet head 22 along the cylinder 11, discharges an oily ink to the material 9 according to a discharging position and the areal rate obtained by the calculation, and forms a halftone dot image responsive to an original with the ink. This operation is continued until the cylinder 11 is rotated one revolution, an oily ink image of one color of the original is formed on the material 9 to prepare a press plate. Then, an ink jet recorder 2 retracts to separate from the cylinder 11. The cylinder 11 is preferably grounded to become an opposite electrode in the electrostatic field discharging. |
