PURPOSE: To obtain prints of which the tones always conform to reference tones of the prints, by a method wherein in addition to the adjustment of a feed quantity of ink with a color sensor, a sensor which measures the thickness of a water film on the plate surface of each color is provided and the feed quantity of water is also adjusted at the fixed rate.
CONSTITUTION: A water film thickness sensor 18 measuring a thickness of a water film on a plate surface concerning each color is used and a signal from the sensor is transmitted to a controller 3. When there is any deviation by comparing the signal with a reference value herein, a command signal is given to a motor 19 for rotation of a water source roller so as to make the deviation zero. By repeating this procedure from one minute to the next, the thickness of the water film on the plate surface of each color is always kept constant. In order to control the thickness of the water film on the plate surface of each color at a fixed value, a detction signal 20 from each water film thickness sensor of four color printing units and the command signal 21 to each motor for rotation of water source roller are inputted to and outputted from the controller in addition to the case of ink film thickness controlling.
ISONO HITOSHI
ITAYA SHIGERU
