Roll-to-roll (R2R) printing technique has gained significant attention for fabricating flexible
electronic devices such as OTFT, RFID tag, flexible PCB, sensors due to its characteristics
of high throughput and large area. Because of the demand for device miniaturization leading
to high-speed operation and high level of integration, the highly accurate register control is
crucial in both the x-axis (MD - machine direction, refer Fig.1) and y-axis (CMD – cross
machine direction). As a result, there have been stringent requirements on precision control
of tension, lateral, registration even with roll eccentricity, un-uniformity, bearing noise. While
there have been a number of studies on register control, tension control, as well as lateral
control, there are few reports on controlling high accuracy (e.g. less than ±10 µm) of moving
webs in the x, y-axis.
In this report, an AMBR (active motion based roller) system which has max. 5 degrees of
freedoms is suggested for the control of the web position in both the MD and CMD. The
AMBR system is able to rotate around z-axis at a center point as we move the left and the
right side of an active roller amount of x1 and x2 in xy-plane. The positioning of a moving web
obeys the normal entry law (i.e. the web tracks laterally on roller surface until it is once again
perpendicular to the roller axis). Therefore, the control of displacement x1 and x2 could be
used to control precisely the position of the moving web in CMD. For the precision control of
tension and register, the left and the right side of an active roller can be used to compensate
the web elongation, which induces the tension variation as well as overlay alignment.
An AMBR system has been designed for controlling the moving web position in both the MD
and CMD. First, the mathematical model was suggested based on the previous studies.
Second, the simulation analysis was implemented to define the operating range of the AMBR
system. Finally, the performance of the AMBR system was verified by experiment. The
experimental results showed that the AMBR system can be used to control the position of
moving web within ± 10 -15 µm in MD and CMD.