非晶矽薄膜電晶體液晶顯示器閘極驅動電路之研究

Abstract

薄膜電晶體液晶顯示器(thin-film transistor liquid-crystal display,簡稱TFT-LCD)是利用兩片玻璃基板中間夾雜著一層液晶分子,上層的玻璃基板主要是和彩色濾光片做結合,而下層的基板則有電晶體嵌於基板上方,當電晶體打開,電流通過電晶體時會對液晶分子產生電場變化,液晶分子隨著電場變化做不同角度的偏轉,藉以改變光線的偏極性,配合固定背光源的光度,再透過濾光片來決定不同畫素的明暗狀態,最後經過彩色濾光片,構成了面板出現的影像。為了使面板可以顯示正確的影像，一般都是以外部連接的IC晶片來提供面板所需要的驅動電壓。近年來為了達到輕薄化和節省成本的目標，採取Gate driver On Array (GOA) 的驅動方法可以有效的減少外部IC晶片的數量和生產成本。因此，如何以有效率的設計達成高穩定性，低功率消耗，多功能的GOA電路是目前在正被廣泛研究的課題。 在本篇論文中,提出三種GOA電路來解決不同的問題。先提出了第一個電路來達到最小面積的目標,再針對極性反轉的功能設計出第二的電路，最後提出GOA(III)以實現高穩定性和低功率消耗的電路給高解析度液晶顯示器使用。而電路是用非晶矽薄膜電晶體(Amorphous Silicon TFTs,簡稱a-Si TFTs)作為電路的驅動元件。雖然非晶矽薄膜電晶體電子遷移率低,但是它的高均勻性和低成本，是做為產品化的最優先考量。這三種GOA電路可提供給不同需求的面板，並可實現高穩定度及高解析度的TFT-LCD。

Thin-film transistor liquid-crystal display(TFT-LCD) uses a layer of liquid crystal molecules placed between two pieces of glass, the upper glass is mainly bound with color filters, while the transistors are embedded in the top of lower glass, when the transistor is turned on, the current which pass through the transistor change the electric field for liquid crystal molecules. With the different variation of electric field, the molecules are rotated for different angles and change the polarity of light. By cooperating with fixed backlight and filters determines the light and dark condition in pixels, finally the light through the color filters produces the image which appears in a panel. In general, external bonding IC chips provide the driving voltages of panel and let the panel shows the correctly picture. In recent years, the driving method of GOA can reduce the numbers of external IC chips and the cost of fabrication effectively in order to realize the slim and low cost display. Therefore, how to achieve the high reliability, low power and multi-function GOA circuit by effective design is the main subject which is being extensively studied. In this thesis, three kinds of GOA circuits are proposed to solve the above issues. The first GOA circuit is proposed to achieve the goal of minimum area. Then, the second GOA circuit is designed to realize the function of polar inversion. Finally, the third GOA circuit is proposed to obtain high reliability and low power circuits for high resolution TFT-LCDs. However, the circuits use amorphous silicon TFT, referred to as a-Si TFTs as the driving devices. Although a-Si TFTs has low mobility, the high uniformity and low cost of a-Si TFTs are the priority consideration for mass production. The three type of GOA circuits provide to different requirement of panel and achieve the goal for high reliability and high resolution TFT-LCDs.