| 摘要 |
PURPOSE:To constantly supply an optimum amount of dampening water in accordance with various printing conditions to prevent a stain in printing and a reduction in ink density by a method wherein while opening/closing solenoid valves are controlled in accordance with the rotating speed of a lithographic press and the density of a printed matter, dampening water forcibly fed is jetted. CONSTITUTION:The title apparatus consists of a speed detection means 1, a water jetting means 2, a water supply means 3, a control means 4, and a printing density detection means 9. On the other hand, an offset printing plate 6a is wound on a plate cylinder 5a of a lithographic press. At this time, the speed detection means 1 detects the rotating speed of the plate cylinder 5a by a detector 15. The printing density detection means 9 detects the density of a printed matter 10 by detection sensors 9a-9d each provided with a plurality of light emitting elements and photodetectors. Based on the rotating speed and printing density, the control means 4 controls the opening/closing of opening/closing solenoid valves 22a-22d corresponding to jet nozzles 21a-21d of the water jetting means 2. In this manner, an optimum amount of dampening water is constantly supplied. |
