氫化非晶矽薄膜電晶體因其製程成熟、低製作成本及高度均勻性，廣泛應用於主動式矩陣液晶顯示器中，且在可見光照射下能根據亮度大小產生相對應之光電流，藉此將光學訊號轉換為電訊號並可輕易實現輸入光源的位置偵測，使得氫化非晶矽薄膜電晶體成為光學互動顯示器中光感測器及周邊驅動電路的理想製程選擇。然而當光感測電路整合於顯示面板中，共用控制訊號使得周邊驅動電路之負載上升，傳統架構因氫化非晶矽薄膜電晶體載子移動率較低將導致驅動能力不足。此外，由於環境光也屬可見光波段，將使氫化非晶矽薄膜電晶體產生較高之光電流而導致光感測器誤輸出。因此，加強氫化非晶矽薄膜電晶體之驅動能力及改善光感測器於環境光中之可靠度，是整體實現光學互動顯示器之重點。
本論文之主旨為針對基於氫化非晶矽薄膜電晶體之光學互動顯示器提出兩個可增強驅動能力之閘極驅動電路，並提出一個共用環境光補償架構且可同時偵測三種光學輸入訊號之精簡光感測電路。此外，針對光感測電路於環境光操作之可靠度，提出改善感測薄膜電晶體元件長時間老化問題之驅動方法，並藉由探討薄膜電晶體在不同色溫之白光照射下產生之光電流差異，進一步分析光感測電路於不同應用環境時之穩定性。本論文第一個電路為使用二階段抬升架構改善輸出波形上升及下降時間之閘極驅動電路，藉由將驅動電晶體閘極電壓在電路輸出點開始充電及放電前抬升至更高電壓，可在不加大元件的尺寸下達到增強驅動能力的效果。第二個閘極驅動電路則是進一步改善驅動電晶體閘極電壓抬升時受到寄生電容及臨界電壓影響之問題，提出利用額外直流電壓準位之驅動方法，可使驅動電晶體之閘極電壓在電路操作各階段維持在更高準位，大幅改善電路之驅動能力。第三個電路為光感測電路，其使用結合傳統彩色濾光片之非晶矽光學薄膜電晶體，此電路可同時偵測三種不同顏色之雷射光筆訊號，且輸出結果不受環境光強度所影響，使光學互動顯示器具有更高的感測器密度並提高位置偵測之準確度。
另外，本論文藉由探討氫化非晶矽薄膜電晶體在長時間偏壓的光電流特性變化，提出降低閘極偏壓之驅動方法藉此延長整體感測模組之使用壽命，並建立薄膜電晶體光電流之等效模型，同時以HSPICE模擬及實際電路量測驗證提出方法之可行性。在論文的最後則探討覆蓋不同彩色濾光片之薄膜電晶體照射不同色溫白光時產生光電流的差異，藉由量測到之光電流比例推測不同色溫白光在可見光波段的能量分布與彩色濾光片的相對穿透度的相對關係，可作為設計感測器元件尺寸之參考，並以不同設計參數之光感測電路驗證在不同色溫白光照射下皆可以維持正常操作，確保光學互動顯示器在不同環境下之穩定性。

Hydrogenated amorphous silicon thin-film transistors (a-Si:H TFTs) have been widely used in active matrix liquid crystal displays (AMLCDs) due to their mature process, low fabrication cost, and high uniformity. Moreover, a-Si:H TFTs can generate corresponding photocurrents according to the intensity of illuminated visible light. By transforming optical signals into electrical signals, detecting the position of the optical input signals can be easily realized. These characteristics make a-Si:H TFTs an ideal choice for the process of optical sensors and peripheral driver circuits for optical interactive displays. However, when the optical sensors are integrated into the pixel matrix of displays, the control signals of the optical sensors are shared with those of the pixel circuits, increasing the loadings of the driver circuits. The conventional structure cannot provide sufficient driving capability due to the low mobility of a-Si:H TFTs. Since the ambient light belongs to the category of visible light, a-Si:H TFTs under illumination also induce large photocurrents, leading to false detection. Therefore, improving the driving capability of a-Si:H TFTs and enhancing the reliability of optical sensors under illumination of ambient light are both significant in realizing optical interactive displays.
This dissertation proposes two gate driver circuits for enhancing driving capability, and one optical sensor that can detect three optical input signals and uses only one ambient light compensation structure. In addition, a driving method to improve the degradation of the sensing TFT is proposed. To analyze the reliability of the optical sensors under different circumstances, differences among the photocurrents from TFTs under illumination of white light with different color temperatures are investigated. This first proposed circuit is a gate driver that uses its two-step-bootstrapping structure to improve the rising and falling times of the output waveforms. The gate voltage of the driving TFT is increased to higher voltage levels before charging and discharging the output node, enhancing the driving capability without enlarging the size of the driving TFT. The second proposed gate driver circuit uses an additional direct current (DC) voltage level to improve the increase of the gate voltage affected by the parasitic capacitance and the threshold voltage. The gate voltage of the driving TFT can be maintained at higher voltages during the circuit operation, enhancing the driving capability of the circuit. The third proposed circuit is an optical sensor that uses a-Si:H TFTs combining the processes of conventional color filters. The proposed optical sensor can detect the optical signals of three colors coming from the laser pointers. A simple ambient light compensation structure is used to prevent intense ambient illumination from affecting the sensing results, increasing the sensor density of an interactive display, and thereby achieving accurate detection of the position of the optical inputs.
Furthermore, this dissertation investigates the changes in photocurrent from a-Si:H TFTs under long-term stress, and a driving method is proposed for extending the lifetime of sensing structures. Models of the photocurrents of the TFT are established, and the feasibility of the proposed method is verified by simulations and measurements. Finally, the differences of photocurrents induced by a-Si:H TFTs are investigated under the illumination of white light with different color temperatures. The effective illumination of white LEDs passing through different color filters can be deduced using the current ratios obtained by TFTs covered with different color filters. Thus, the reference of designing the sizes of devices in optical sensors is established, and its feasibility is verified by the fabricated optical sensors with different designed parameters. The optical sensor operates without false detection under illumination of white light with different color temperatures, ensuring the stability of optical interactive displays under different circumstances.

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