新型感測系統應用於可撓曲式觸控面板

Abstract

投射電容式觸控面板的原理為自手指靠近面板時造成電極互電容的微小變化，此變化即可判斷是否有觸碰，傳統上，使用輸出電壓表示互電容的微小變化，決定是否有觸碰。本篇論文提出了一種新型觸控面板電路，此電路利用時間差的概念去表示互電容的微小變化，可以由時間差決定是否有觸碰。此電路利用史密特觸發器將雜訊濾除並使電壓轉為時間，此時間差可用計數器將時間轉為數位訊號輸出。觸碰面板電路不需類比對數位轉換器(ADC)，應用於觸控面板的ADC需要高速且高解析度，此要求大大增加了實現此ADC的困難與複雜，由於不需ADC，所提出的觸控面板電路的佈局面積會減小。本電路結合了類比電路與數位電路兩部分，類比電路包含電荷放大器、差動放大器和史密特觸發器，數位電路包含計數器、時脈產生器和切換時間邏輯電路。實驗結果呈現此觸控面板電路是可行的，且可判別是否觸碰。本論文所提出的電路，使用TSMC 0.18um 1P6M製程與實現。此晶片面積為1.216mm2。

The principle of the projected capacitive touch panel is used to sense the variations of mutual capacitances both before and after touching. Typically, touch panel circuits often sense the output voltage to determine touching the panel or not. The novel touch panel circuit proposed in this study uses the concept of the time differences to determine touching the panel or not. The proposed touch panel circuit uses the Schmitt trigger to eliminate the noise and be considered as voltage-to-time converter. The time differences is converted into digital signals via counters and time-to-digital converters. The proposed circuit does not need the analog-to-digital converter (ADC), which has the features of high speed and high resolution, bringing about a new complicated problems to realize the ADC. The experimental results show the proposed circuit can be applied to touch panel. The proposed circuit is simulated and fabricated via the TSMC 0.18um 1P6M process, and the area of the IC is 1.216mm2.