Robust, Reliable and Repairable Inkjet Print Head with Dynamic Drop Modulation Feedback for Printable Display Applications

Abstract

With the advent of Liquid Crystal Display (LCD) and Flexible Display (FD) applications, a number of research and development companies have been pursuing mask-free digital inkjet printing processes to keep manufacture simple, low cost and environmentally friendly for instant, color filter pixelization, color filter black matrix application, polyimide coating, ball spacer, liquid crystal dispensing and light guide micro-lens deposition of back light unit and so forth. As a result, the key challenge is to not only control the drop placement accuracy but also provide sufficient drop volume uniformity control and real-time waveform modulation to meet the critical requirements. This paper focuses on the recent developments of a robust, reliable and repairable print head along with Addressable Waveform Trimming Circuit (AWTC) to enable drop placement accuracy and drop volume uniformity over 256 nozzles and 4-inch print width. Also reported is both the print head and the drive feedback system for the case of pixel-by-pixel dispense of red, green and blue Cholesteric Liquid Crystal (ChLC) which has been widely applied to bi-stable reflective display applications.