Dynamic ink-jet printing analysis system with addressable waveform trimming

Abstract

Definitely the ink jet fabrication is an expectable technology for the fields of display and semiconductors, such like for the fabrication of color filters, the forming of metal circuits, the dispensing of liquid crystal, and for the further continuous manufacture of flexible displays etc. Recently, inkjet printing technologies have been rapidly developing and are not only for the diminished size of the drops to the pico-liter, the multiplex driving scheme, or for the real-time observation technology which led to the improvement of the inkjet printing performance, and which realized the pixel-to-pixel control. In this article, an electrical controller is designed to differentiate the waveform for each nozzle synchronously, to compensate for the nozzle cell deformation and pressure drag loss during inkjet firing at high voltage, and for a high frequency named addressable waveform trimming circuit (AWTC). The controller is composed of a high voltage control block which drives each nozzle, an FPGA chip to multiplex the high voltage output, an AID converter which transfers an analog signal into a digital signal and then into FPGA, a differential signal input to FPGA as feedback to correct analog output, which gives a real-time tracking of jetting quality to verify the nozzle-to-nozzle variation. For dynamic feedback of the drop variation in real jetting, this AWTC accepts correction signals by a machine vision system synchronously with the firing trigger in order to analyze the individual captured images. The maximum support nozzle channel is up to 1280 and can be handled within a 2% jetting accuracy.