Reduction of Linearly Varying Term of Register Errors Using a Dancer System in Roll-to-Roll Printing Equipment for Printed Electronics

Abstract

Roll-to-roll printing equipment can be used to manufacture flexible electronic devices with multilayer structures. This manufacturing process requires both precise tension control of the web and high register accuracy between printed layers. Because of the high temperature of the dryer required for sintering inks, the web after printing undergoes considerable shrinkage. This shrinkage brings out an accumulated phase difference between each of the printing layers and a linearly varying term in the register errors. This error can be removed by elongating the shrunk web, or by transferring the web at the same linear velocities using rollers with identical diameters. However, the elongation causes high increase in tension that can damage the previously printed layer. Moreover, a very small difference between the diameters of the printing rollers because of the tolerance in the machining process of the roller can still produce a linearly varying term in the register errors although the web has recovered from shrinkage. This paper proposes a linear dancer system to remove the linearly varying term of the register errors caused by small difference in the diameters of the printing rollers. The dancer system is designed to synchronize the velocity of the second printing roller with the movement of the dancer to ensure that the dancer controls the tension within a limited range of movement of the dancer. Simulations as well as experiments show that the proposed dancer system and control method can eliminate the linearly varying register error and control the tension effectively. As a reverse application of the proposed method, it is also presented that a larger difference between the diameters of the printing rollers can decrease the stabilized tension for elongating the web to compensate for the shrinkage, which can reduce possible damage to previously printed layers during the manufacturing process of printed devices.