A Design of the AMBR Systems for Precision Control of Moving Webs in Machine and Cross Machine Direction

A Design of the AMBR Systems for Precision Control of Moving Webs in Machine and Cross Machine Direction

Kee Hyun Shin
TOBA

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.