received actual roller surface linear velocity signal and theoretical roller surface linear velocity signal of each roller so as to allow the actual roller surface linear velocity of each roller to be consistent with the theoretical roller surface linear velocity of each roller thereby completing the roller coating transfer of the first roller coating unit in the present embodiment in order to realize continuous operation of adjacent roller coating units on line distance data between the first roller coating unit and the second roller coating unit is input into the plc control module and on the basis of the process speed and the distance data the plc control module is adapted for calculating out a time to start the second roller coating unit in the present embodiment the plc control module is a servo motor which has a data collector used for collecting the process speed signal a calculator used for calculating out the theoretical roll surface linear velocity and a comparator used for comparing the theoretical roll surface linear velocity with the actual roll surface linear velocity in the present embodiment in order to print irregular long patterns a code recognition module is further comprised and the printed patterns.