壓電噴墨頭驅動條件與墨滴行為之研究

Abstract

隨著半導體技術與材料科學的發展，工業用印刷技術逐漸成為先進製程技術研發重點之一，例如三維噴蠟機、印刷電路板打樣噴墨機、薄膜電晶體噴墨、太陽能電池電極製作、生醫晶片酵素噴印製程等。 一般噴墨驅動系統通常多會利用數位/類比轉換器搭配放大器作為噴墨頭驅動訊號產生器之設計與實現的方式。然而此種方式可透過放大器或驅動積體電路雖可達到較佳的線性效果，但對於長時間操作於高頻環境下，易生成高溫與廢熱，且當運用在多變化的應用中，可能同時有多組負載需要一種或多種驅動訊號來達成功能，不僅需搭配散熱系統或額外的降溫裝置，體積大、單價高因素等都是實現多通道負載驅動電路時的必定遭遇的困難與挑戰。 因此，本文藉由可調變開關控制驅動電路，以半橋式電路為驅動電路之硬體基礎，搭配軟體影像擷取噴墨頭墨滴飛行狀態，探討不同的驅動條件對噴墨狀態之影響，結果顯示(1)驅動電壓振幅越大則墨滴飛行速率越高，兩者呈現性關係，相關係數為0.99；(2) 驅動電壓越高，則墨滴直徑相對越大，調變振幅對墨滴直徑平均相關係數為0.983；(3)驅動電壓頻寬操作於16us~24us間，不論驅動電壓由55V漸增至75V，墨滴長度皆會提升造成衛星液滴風險性則會提升。

The Industrial InkJet Printing technology such as 3D printer, solar cell electrode process and bio chip manufacturing has gained substantial interests due to the progress in materials science and semiconductor manufacturing technology.

The InkJet driving system is typically implemented by D/A converter and OP amplifier to provide better linear operation ability and performance. However, this design suffers from extra heat generation and high cost during long-time operation. Therefore, an alternative design is necessary in order to reduce the cost of driving circuits and achieve the multi-channels driving purpose.

In this study, we implement the piezoelectric inkjet nozzle driving circuit based on half bridge structure to form the ink droplet as well as controlling their properties such as dimension and velocity through the image capture system. The objective of this study is to investigate the droplet behavior formation through the driving waveform modulation, and the results show that (1) the correlation coefficient of driving voltage amplitude to velocity ratio is 0.99, (2) the correlation coefficient of voltage to diameter ratio is 0.983, and (3) when the driving waveform pulse width is modulated between 16 and 24 us, the droplet length will increase and in turn enhance the risk of satellite droplet.