薄膜電晶體為主動式有機發光二極體顯示器面板電路內之主動元件，主流製程包含低溫多晶矽薄膜電晶體、非晶相銦鎵鋅氧化物薄膜電晶體，與氫化非晶矽薄膜電晶體。低溫多晶矽薄膜電晶體與非晶相銦鎵鋅氧化物薄膜電晶體因具有極佳的電流驅動能力，因此分別為中小型與大型尺寸主動式有機發光二極體顯示器之驅動元件。然而低溫多晶矽薄膜電晶體製程於面板不同位置之雷射退火溫度不一致，導致不均勻電晶體元件電氣特性，例如臨界電壓變異等，將產生驅動電流失真。不同製程下非晶相銦鎵鋅氧化物薄膜電晶體有常關型與常開型兩種特性，而常開型非晶相銦鎵鋅氧化物薄膜電晶體將會造成多數畫素電路的補償操作失敗。另一方面，由於氫化非晶矽薄膜電晶體於可見光頻段具有敏感之光感應特性，因此整合於玻璃基板之氫化非晶矽薄膜電晶體光感測畫素電路亦逐漸受到重視。
本論文分別針對小尺寸、中尺寸及大尺寸高解析度有機發光二極體顯示器面臨之議題提出三個新式畫素補償電路，以及針對採用光筆觸發之大尺寸光感測互動式面板提出一新式光感測補償電路。第二章提出之3T2C精簡畫素電路適用於7吋720P主動式有機發光二極體顯示器。此電路可補償低溫多晶矽薄膜電晶體臨界電壓變異，同時避免可攜式面板之閃爍現象而提高畫面對比度。研究結果顯示薄膜電晶體臨界電壓變異量為±0.5 V時，電流誤差率皆低於5%而達成高均勻性驅動電流。然而此電路之驅動電流受電源影響，當面板尺寸上升使電源線壓降逐漸明顯時，同樣將導致面板驅動電流不均勻。因此第三章提出採用低溫多晶矽薄膜電晶體且適用於15吋2160P面板之驅動法，此驅動法首次提出可同時實現臨界電壓補償、飄移率補償、電源線壓降補償、支援高速操作、無閃爍現象且不需任何參考電壓線之5T2C畫素電路。為了產生驅動此5T2C畫素電路所需之特殊訊號線波形，具有6T1C精簡架構之閘極驅動電路同時被提出。模擬結果驗證不論薄膜電晶體特性變異或面板尺寸上升所造成之電源線壓降，本驅動法皆可在6微秒內之資料線高速操作時間後產生均勻之驅動電流以實現高品質顯示畫面。針對大尺寸面板之元件需求與規格，第四章提出適用於大尺寸120 Hz 2160P面板之非晶相銦鎵鋅氧化物薄膜電晶體畫素電路。針對非晶相銦鎵鋅氧化物薄膜電晶體之常關型與常開型電氣特性，此電路首次提出採用源極隨耦架構實現補償正負值臨界電壓，並且偵測有機發光二極體元件之臨界電壓提供額外驅動電流以改善老化所造成亮度衰減之畫素架構。此畫素電路於常關型與常開型驅動薄膜電晶體之臨界電壓飄移1 V的情況下，電流誤差率皆在3.5%以內；於有機發光二極體臨界電壓飄移0.5 V並且輸入不同資料電壓時，對應亮度誤差皆在5%以內。第五章提出適用於大尺寸光感測互動面板之光感測補償電路，此6T1C光感測補償電路採用氫化非晶矽光感應薄膜電晶體配合彩色濾光片補償環境光影響所致錯誤偵測，同時首次提出以一主動式負載產生修正電流以抵銷反射光所誘生之光電流。量測結果顯示此電路於12560照度之環境光與588照度之反射光皆可正確偵測光筆光源而無電壓誤輸出。

Thin-film transistors (TFTs) are used as the active devices of driver and pixel circuits for active-matrix organic light-emitting diode (AMOLED) displays, including low-temperature polycrystalline-silicon (LTPS) TFTs, amorphous indium-gallium-zinc-oxide (a-IGZO) TFTs, and hydrogenated amorphous silicon (a-Si:H) TFTs. LTPS TFTs and a-IGZO TFTs are regarded as the mainstream technologies employed in small/ medium-sized and large-sized AMOLED displays respectively for their superior current driving capability. However, temperature fluctuation of excimer laser annealing throughout the glass substrate gets rise to non-uniform characteristics of LTPS TFTs, such as the threshold voltage variations, resulting in non-negligible deviations in the OLED currents. The a-IGZO TFTs exhibit normally-off or normally-on characteristics depending on the fabrication process, and the normally-on characteristics lead to the false threshold voltage detection of most the compensation pixel circuits. On the other hand, because of the high photosensitivity of visible light, a-Si:H TFTs have gained much attention for the application of optical sensors integrated into glass substrates.
This dissertation proposes four new compensation circuits for small-sized, medium-sized, large-sized AMOLED displays and pen-writing interactive whiteboards, respectively. In Chapter 2, we propose a simple 3T2C pixel circuit for the 7-inch AMOLED panels with high-definition resolution (1280×720, 720P). The proposed 3T2C pixel circuit has immunity against the threshold voltage variations of LTPS driving TFT and avoids an apparent image flickering phenomenon. Based on the simulation results, the relative current error rates among the entire data voltage range are all below 5% with ±0.5 V threshold voltage variations of the driving TFT. However, this pixel circuit is incapable of compensation for power line voltage drop caused by the increase of the panel size. Therefore, chapter 3 proposes a driving scheme based on 15-inch 2160P (3840×2160) AMOLED panels to carry out high-speed operation with constant VDD and VSS, free from image flickering, no requirement of extra reference line, and VTH/ mobility/ VDD compensation. To generate the special control signal for the proposed 5T2C pixel circuit, a new gate driver circuit of concise 6T1C structure is proposed as well. The simulated results show that the proposed driving scheme can generate uniform OLED currents regardless of the TFT characteristics variations and the voltage drop of the power line within the row time of 6 μs. For the specification requirement of large-sized panels of 2160P at 120 Hz frame rate, chapter 4 proposes a new compensation pixel circuit based on a-IGZO TFTs for compensating for the threshold voltage shift of driving TFT by the new source-follower structure. In addition, it detects the threshold voltages of the OLED and enlarges the driving current to maintain stable luminance. The electrical characteristics of the OLED device were experimentally measured and the simulation parameters were extracted for HSPICE simulations. According to the simulation results, the current error rates are within 3.5% for the proposed 5T2C pixel circuit under 1 V shift in threshold voltage of normally-off and normally-on driving TFTs. Moreover, deviations of the normalized luminance of the proposed pixel circuit are below 5% for different data voltages. Thus, the proposed 5T2C pixel circuit has high immunity against the VTH shift of the a-IGZO driving TFTs and luminance drop of the OLED device. Chapter 5 proposes a new optical sensor circuit to compensate for the ambient light effect for large-sized optical interactive panels based on a-Si:H photo TFT with RGB primary color filters. An active load is added into the pixel sensor to ameliorate the reflected light effect. Experiments show that the proposed optical sensor generates correct voltage outputs in ambient light with an intensity of 12560 lux and avoid false detection under reflected light with an intensity of 588 lux.

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