Printing pressure uniformization of a roll-to-roll system using roll runout

Printed electronics refers to the technology of fabricating electronic devices by applying the printing process method to thin films. Printed electronics is regarded as a promising industry of the future because of its relatively low cost, simple process, and high mass production capacity, which are all superior to existing manufacturing methods. Roll-to-roll printing is a suitable technology for printed electronics with large-scale and high-speed mass production. To commercialize roll-to-roll printing technology, it is necessary to develop technology for position control of the web, tension control of the web, printing pressure control, and functional ink development. Among them, the printing pressure uniformization by the printing pressure control is an important factor that significantly affects the printing quality. In the roll-to-roll printing process, the functional ink is transferred by the nip generated by the printing pressure. That is, if the nip can be kept uniform by applying the printing pressure uniformly, the uniformity of the line width and thickness of the printed pattern is improved. This nip occurs on a line connecting the geometric center of the two rolls, and the centers of the two rolls are on the orbit line by each roll runout. Therefore, the print pressure can be estimated through the change in the inter-center distance of the rolls caused by the roll runout. In this study, we propose a method of printing pressure uniformization using roll runout. After establishing initial conditions that minimize change in printing pressure, load cells are used to estimate and verify the initial conditions that minimized the change in the inter-center distance of rolls, and pressure sensitive paper is used to verify whether the actual printing pressure is minimized.