Register mark measurement errors in high-precision roll-to-roll continuous systems: the effect of register mark geometry on measurement error

It is important to achieve high-precision register control in roll-to-roll continuous printing systems. Thus far, many studies on the dynamics of registers and tension and on register control techniques have identified register control as a problem of controlling and minimizing the disturbance of strain of the substrate. However, register control using printed register marks is necessary, and printing defects in creating these marks cause measurement errors. This study demonstrates by experimental verification that the measurement error is generated by the widening and agglomeration of the register mark. Furthermore, the error is shown to differ with the size and shape of the mark under identical printing conditions. The results illustrate the importance of improving the printing quality of the register mark, selecting the desired geometry for register marks with regard to printability, and utilizing an edge-detection algorithm in the control program for high-precision register control.