Error Diffusion based Feedforward Height Control for Inkjet 3D Printing

Inkjet 3D printing is capable of building high-resolution components layer by layer with polymer-based materials that can also include functional components. Currently, most inkjet 3D printers are operated with prescribed layer structures to achieve a desired geometry and, in particular, a desired heigh profile. This often leads to discrepancy between target geometry and actual products. This article presents a framework to leverage halftoning processes in inkjet printing of images to inkjet 3D printing to improve geometric integrity and specifically a more precise height profile. By using the existing imaging pipeline, this framework requires no modification to current hardware. Halftone is a fundamental step in imaging pipeline for all digital printing systems. Error diffusion is one of the most common and widely used halftone algorithms. In this work, we will use two different error diffusion kernels, the 2 × 3 Floyd and Steinberg (FS) kernel and the 3×5 Jarvis, Judice and Ninke (JJN) kernel to demonstrate the feasibility and improve height profile control of an inkjet 3D printer using UV curable inks. The current implementation operates in a feedforward manner using a previously validated 2D height profile model to provide heigh estimation after the deposition of each layer. Two 3D geometry samples are printed using the proposed approach. Consistent RMS height profile errors and standard deviations from different samples demonstrated the effectiveness of the proposed approach to improve height profile tracking in inkjet 3D printing.