To provide a method and an apparatus for on-press plotting lithographic printing capable of dealing with digital image data and printing many printed products of a clear image at a high speed and low cost.
In the case of plotting by using an ink jet method for discharging an oily ink from a recording head having a plurality of discharging channels by utilizing an electrostatic field, main scanning is conducted by a rotation of a plate cylinder for mounting a plate material, and in the case of plotting while moving a discharging head in parallel (sub-scanning direction) with an axis of the cylinder, a sub-scanning movement of the discharging head is continuously conducted at a constant speed [X*(N/K)+1] [dots/one cycle] by using the discharging head having discharging channels of [X*(N/K)+1] [pieces], wherein a plotting resolving power on the plate material of the sub-scanning direction is N [dots/25.4 mm], a channel density of the discharging head in the sub-scanning direction is K [dots/25.4 mm] and an arbitrary positive integer is X.
OGUCHI HIDEYUKI
ISHII KAZUO
KATO EIICHI
