使用非晶矽薄膜電晶體的內嵌型主動式大尺寸面板觸控電路

Abstract

本論文提出一種新型的內嵌型主動式大尺寸面板觸控電路，此電路使用投影電容式觸控技術並適合操作在 IPS (In-Plane-Switching) 液晶的種類下。投影電容式觸控技術主要透過偵測觸碰物當作導體與共電極之間所產生出來的觸控電容，來分辨是否觸控，但當觸控電容變化過小時，容易造成外部觸控IC的偵測，並增加IC計算的複雜度與投影式面板的價格。相較於傳統的電容式觸控顯示技術，主動式觸控電路增加額外的TFT，但可增大感測電流並易於透過外部的OP放大器讀取。此外，為了實現大尺寸的觸控電路，我們對電路的面積做了評估，並設計出符合規格的觸控單元。進一步的，我們設計出了觸控單元內的各個子畫素並探討之間的功能與電路模擬情形。並且，我們評估整個觸控單元在大尺寸面板的四個角落上的情況，並分析近端與遠端感測的觸控電流差異。最後，我們評估了電路的視覺影響並提出了見解與看法。

In this thesis, we propose a novel in-cell active touch circuit for large size panel. This circuit uses projected capacitive touch technology which is suitable for operating in IPS (In-Plane-Switching) liquid crystal. Projected capacitive touch technology senses the touch capacitance formed between the common electrode and the touch finger to distinguish touch or no touch. When the change of touch capacitance value is small, touch signal is hard to be read by IC and the IC must be very sensitive and complicated to do computation, which makes the projected capacitive touch panel expensive. Compared to the conventional projected capacitance technology, active touch circuit using additional TFTs senses but enlarges the current signal by the external OP Amplifier. Besides, in order to implement the touch circuit in large size, we evaluate the area of the circuit and design the suitable sensor pad. Further, we design the sub-pixels with different functions in one sensor pad and simulate these circuits. Then, we evaluate the sensor pads at four corners of a large panel by simulating the difference of current between near point and far point. Finally, we study the visual effect for the display panel and propose proper solutions.