應用於液晶顯示器面板之非晶矽薄膜電晶體閘極驅動電路技術

Abstract

在薄膜電晶體液晶顯示器(thin-film transistor liquid-crystal display，簡稱TFT-LCD)驅動系統中，閘極驅動電路，gate drivers(或稱掃描驅動電路，scan drivers)，主要負責將畫面上一列列的電晶體依序打開，讓資料電壓能夠進入到液晶及儲存電容內。近來，在消費性產品中，閘極驅動電路部分已高度整合於下層玻璃基板，而非傳統使用IC晶片的型式。目地在於降低成本與使LCD模組更輕薄，雖然非晶矽薄膜電晶體(a-Si TFTs)的電子遷移率低，但其高均勻性及低成本，適合閘極驅動電路的實現。 此論文中，提出兩種主要的電路型態(Type A與Type C)。Type A主要目的是達成低雜訊及穩定的波型；而Type C電路，其目的是達到低功耗並且運用在窄邊框面板上。另外，根據Type A和Type C電路，分別修改成適合雙向掃描的電路(Type B和Type D)。於是在產品化時，能夠有更靈活的應用。 所有提出的電路，最終目標是達成與面板整合做測試，故為了符合整個面板的規格及實際商用IC訊號，所以在電路上需調整。此外，還必須了解元件均勻度和穩定度。透過多次的電性量測與元件劣化實驗，可以印證在長時間操作之下，此電路依舊能正常驅動面板。

In the driver system of thin-film transistor liquid-crystal display (TFT-LCD), gate drivers (or scan drivers) are the essential parts that sequentially control the gates of pixel TFTs. Therefore, the pixel TFTs can transfer correct data and store in the liquid crystal and storage capacitors. Recently, in the consumer electronic display products, the gate driver circuits have been integrated into the bottom plate glass of LCD module rather than providing form the conventional ICs. Although the electron mobility in a-Si TFTs is extremely low (≈0.3cm2/V-s), the traits of high uniformity and low cost of manufacturing a-Si TFTs have created the trend towards gate driver on array (GOA). Moreover, the application of GOA decreases the cost of ICs and results in the module lighter and thinner. In this thesis, we have proposed two main kinds of GOA, Type A and Type C. The features of Type A are the low noise and stable waveforms, and the threshold voltage drop cancellation method. On the other hand, Type C circuit is designed for the low power application and applying on the narrow bezel panel. Furthermore, in order to apply on products flexibly, Type B and Type D circuits are revised for the bi-directional function from Type A and Type C circuits, respectively. Finally, all of these circuits must integrate into panels for real assessments. Therefore, these circuits should be adjusted for the real panel specification and commercial IC timings. In addition, the device characteristics have to be well surveyed form several experiments including the uniformity, stability, and reliability. By stress experiments for devices and circuits, the results show the gate driver circuits still work normally after long-term use.