目前壓電噴墨法與熱氣泡噴墨法已成熟且普遍運用於噴墨印表機上，然而面對製作更高解析度與複雜度之圖案需求，因應次世代平面顯示器之彩色濾光片塗佈製程開發、及解決新技術現存問題（如使用噴墨法製程所產生之微衛星點問題等），甚至達到未來奈米科技與生物醫學工程所需之微奈米精密噴塗目的，除了不斷改良上述方法來發展先進的相關設備之外，尋找新的噴墨機制以符合未來需求則是刻不容緩。本研究目的在於尋求並發展新的噴墨塗佈機制－超音波噴墨法，經深入研究其理論與基礎模型，再配合所需條件設計新型超音波微墨滴噴頭結構。聲波聚焦噴墨方法可以分為折射、反射及繞射方式經建設性干涉聚焦產生噴墨現象。本研究所設計之超音波噴墨系統在於使氧化鋅薄膜之換能器產生超音波後，藉由新設計之菲涅爾透鏡折射而在墨水液面附近能量聚焦，由於高聲強與高聲能密度之超音波將因聲波非線性特性致使墨水得以突破其表面張力束縛而噴出形成墨點。本論文研究首先推導符合新改良之基礎超音波噴墨模型，再利用成熟的半導體製程技術得以規劃實現超音波噴墨頭設計，並尋求驗證此機制之可行性方法，同時預先探討該基本噴墨系統設計及製作上可能導致問題的原因。 The ejection mechanism of inkjet printing by piezoelectric actuation or thermal bubble expansion has been drawn attentions for decades. These inkjet-printing approaches are generally employed in the application of personal printing devices. More complicated patterns and higher resolution of pixels are, however, demanded to compose finer pictures. Additionally, mico- or nano-droplet doping technology must be developed for the requirement of MEMS or biomedical engineering. Thus efforts should be taken in to improve these two ejection techniques for higher efficient and accurate printing. In another aspect, more reliable techniques to enhance the yielding and productivity such as drop-on-demand inkjet printing are required for fabricating large-scale color filters of TFT-LCD and PLED. A novel approach of inkjet printing should be developed as an alternative to meet these requirements in addition to improving above-mentioned inkjet printing mechanism. The present study aims to investigate another inkjet approach — ejection by focusing ultrasonic waves. The modeling, design and implementation scheme of ultrasonic inkjet printheads will be described in the thesis. Acoustic inkjet printing or ultrasonic inkjet printing can be achieved by focusing the sound energy through refraction, reflection or diffraction of waves. In the study, the printhead is designed to eject droplets by gathering the energy of in-phase acoustical waves. The ZnO thin film transducer is used to generate plan ultrasonic waves. The ultrasonic plane waves are further refracted in spherical waves by new-designed Fresnel lens and then focused near the ink surface. While overcoming the surface tension, ink droplets are expelled out due to the Langevin’s radiation pressure. This ultrasonic printhead designed and fabricated in the study through developed MEMS technologies has been conducted to verify the novel concept. Moreover, possible reasons affecting printhead performance are analyzed and discussed.
