Inkjet printhead performance enhancement by feedforward input design based on two-port modeling

Abstract

Inkjet technology is an important key-technology from an industrial point of view. Its ability to deposit various types of materials on a substrate in certain patterns makes it a very versatile technology. Though the performance criteria imposed by today's applications are quite tight already, future performance requirements will be even more challenging. At the same time, several operational issues such as residual vibrations and cross-talk limit the attainable performance of inkjet printheads. Current research efforts focus mainly on a mechanical redesign of current printheads to overcome these operational issues. In this research, however, it has been proposed to fully exploit the mechatronic character of an inkjet printhead: the use of a systems and control approach has been investigated to break these boundaries. To that purpose, a model of an inkjet printhead based on bilaterally coupled multiports has been derived that provides an excellent starting point for the control purpose in mind. It has been shown that by the use of lifted Iterative Learning Control based on the obtained model, input wave forms can be designed that damp the residual vibrations after droplet ejection and minimize the effects of cross-talk. Consequently, the performance of inkjet printheads in terms of drop-consistency and attainable jetting frequencies is improved considerably. Also, based on the inkjet printhead model, a fundamental insight has been obtained that provides the indispensable foundation for a future mechatronic redesign of inkjet printheads.