適用於車載產品之高信賴性閘極驅動電路研究

Abstract

本論文主要探討如何藉由GOA(Gate driver On Array)電路的設計，去克服搭載GOA之LCD(Liquid Crystal Display)顯示器切入高利潤車載產品市場無法通過嚴苛信賴性測試的瓶頸。在削價競爭的趨勢下，諸多應用面的LCD顯示器均已經採用GOA設計以省略閘極驅動IC (Intergraded Circuit)(即Gate Driver)，達到節省成本的功效，然而，車載市場由於產品優略可能直接影響到人的生命安全，因此其信賴性規格總是較各類應用別嚴苛許多，再加上地球溫室效應(Greenhouse Effect)日益嚴重，環境溫度變化越來越大，也不斷的突破歷史高溫或低溫，促使車載產品信賴性規格也隨之不斷加嚴，導致基本上是由多個本質性易受電壓或溫度影響，進而延伸特性變異的TFT (Thin Film Transistor)元件架構成驅動電路之GOA設計，至今鮮少平展應用到車載市場；另一方面，車載市場不斷擴大，逐漸出現突破一般矩形架構的Free Form顯示器，採用此任意形狀設計更能符合車輛內裝上的多變，而此架構下，閘極驅動IC勢必得省略。LCD顯示器GOA電路信賴性問題，各LCD廠直覺的會朝向提升TFT元件特性著手，此作法通常必須花費攏長的人力與物力下實驗收數據，而且特性提升到一定程度就會陷入材料或製程極限的瓶頸，TFT元件特性提升幅度也因此受限。此篇論文提出一個高信賴性的GOA電路架構，本質上有許多讓GOA訊號穩定的概念，只要再搭配源極驅動IC (Data Driver)的些微設變，提供額外的訊號進入此電路固定節點，就能發揮此電路最佳特性，大幅提升電路驅動能力，克服嚴苛信賴性測試後電路輸出異常的風險；我們除了經由電路模擬佐證了電路的功效外，再藉由Array基板上實際放置電路(Test-Key)的方式，實測出高溫(90℃)長時間驅動測試後(一般LCD產品環測條件中，持續驅動下最高溫約70℃)，電路輸出變化的趨勢，再次證明此電路構想勢必可以讓搭載GOA設計之LCD產品成功切入車載市場。

The paper is to study about a GOA (Gate driver On Array) design for high reliability Spec. in the equipped application in car. We face the situation of cutting price to gain the orders and markets, so LCD maker adopted the GOA design for many parts of application of LCD display to cost down. Furthermore, the market of car application grows up quickly and “Free Form” (Free shape) design without Gate driver will be popular in the future. Because of the reliability performance of products in the equipped application in car connects with the safety of people’s life, the reliability Spec. is always more rigorous than other parts of application. Besides, since the Greenhouse effect is worse and worse these years, the reliability Spec. is defined more and more rigorous. We know that GOA is a circuit combined with a lot of TFTs(Thin Film Transistor) which is sensitive to the variation of temperature and voltage. Therefore, there is little GOA design in equipped application in car. We’ve been trying to improve the performance of TFT to overcome the reliability issue of GOA design. However, it would take a long time and maybe face to the bottleneck. The paper publish a GOA circuit that can get over the rigorous reliability test. According to the simulation, we make sure the trends are what we expected. Besides, we used the Test-Key (circuit on the Array substrate) to double confirm the actually output waveform of our GOA circuit can show the same trends.