臺灣博碩士論文加值系統

主動式有機發光二極體（AMOLED）由於其比液晶顯示器（LCD）具有的各種優勢，如對比度更高，響應時間更快，更薄，功耗更低，廣視角，可撓性等優勢，因此受到學界以及顯示器行業的關注。近年來，在畫素電路中採用低溫多晶矽薄膜電晶體（LTPS-TFT）和金屬氧化物薄膜電晶體作為AMOLED的背板技術。 LTPS-TFT具有高電流驅動能力和良好的電特性，低溫多晶矽薄膜電晶體因為在製程中經過分子雷射的退火再結晶會導致一些電性上的不均勻，這是一個非常嚴重且不可避免的問題。與LTPS-TFT相比，金屬氧化物薄膜電晶體具有優良的特性，包括良好的遷移率，優異的均勻性和良好的穩定性。它更適合用於製造大尺寸顯示器的製程。然而，當長時間操作時，薄膜電晶體將顯示出不均勻的電特性。
但對於實際的AMOLED 顯示器上，除了電晶體的電特性飄移之外，有機發光二極體的衰退以及寄生電阻和寄生電容帶來的影響也需要在我們設計畫素電路時一併考慮。因此，考慮上述問題後，我們從實驗室所得的氧化銦鎵鋅（IGZO）數據中先建立了一個model 並提出第兩個畫素電路是以氧化銦鎵鋅（IGZO）為電晶體的補償電路，其第一個架構包含了四顆薄膜電晶體和二顆電容，其特點為第一個不藉由外部電路就能進行全面性補償的電路並提供逆偏壓延長有機發光二極體的壽命。根據模擬結果，在電晶體的臨界偏壓飄移正負2Ｖ時，電流的電流錯誤率僅1.3%。
第二個電路是以驅動電晶體的電特性去做改善，提出了一個新式補償電晶體mobility 非均勻性的畫素電路，架構包含了五顆薄膜電晶體和二顆電容，其特點是利用時脈分割，使補償mobility時不受data input的電壓值影響，進而達到良好的補償效果，在driving TFT mobility變化±50%所造成的最大電流錯誤率小於3.8%。最後，藉由電路模擬結果的印證並將其與過去期刊上的畫素電路作比較，顯示出設計的電路有著顯著的特性。

Active-matrix organic light-emitting diode (AMOLED) have attracted attentions among recent research and display industries due to their various advantages over liquid crystal display (LCD), such as higher contrast ratio, faster response time, thinner module, lower power consumption, wider viewing angles and potential flexibility. In recent years, low-temperature polycrystalline silicon (LTPS) TFT and oxide TFTs are adopted in the pixel circuit as a backplane technology for AMOLEDs. LTPS-TFTs have high current driving capability and good electrical characteristics but it suffer from threshold voltage (VT) and the mobility (μ) easily varied during the actual annealing process. Compared with LTPS TFTs, oxide TFTs have much better characteristics including decent mobility, excellent uniformity, and good stability. It is more suitable for fabricate large size display in fabrication process. However, oxide TFT will show non-uniform electrical characteristics when operated for a long time.
For a real display, there exist some other issues such as OLED degradation and IR drop. None of paper reported can comprehensively compensate for the issues of displays by voltage programming pixel circuit. Therefore, in the thesis, we build a model of a-IGZO TFT for SPICE which was fabricated from our lab at first. We propose two pixel circuit on a- IGZO TFT. In the first pixel circuit, it is composed of four TFT and two storage capacitors. It can not only successfully detect the VTH of normally-on and normally-off TFT, but apply reverse bias on OLED. Furthermore, the variation of mobility is also compensated. According to the simulation results, the average current error rates are only 1.3% (ΔVTH =±2V).
The second circuit is based on the electrical characteristics of the driving transistor. A new pixel circuit for compensating for the mobility non-uniformity of the transistor is proposed. The architecture consists of five transistors and two capacitors. The pulse division makes the compensation of the mobility not affected by the voltage value of the data input, and thus achieves a good compensation effect, and the maximum current error rate caused by the variation of the driving TFT mobility by ±50% is less than 3.8%. At last, all of them were verified by SPICE and compared with other pixel circuits from presented paper.

Abstract (in Chinese) I
Abstract III
Acknowledgement (in Chinese) V
Content VI
Figure List IX
Table List XII
Chapter 1. Introduction 1
1.1 Research Background 1
1.2 Organic Light Emitting Diode (OLED) 4
1.2.1 What is OLED? 4
1.2.2 OLED structure and operation 5
1.2.3 PMOLED 7
1.2.4 AMOLED 7
1.2.5 Advantages of OLED 8
1.3 Three-dimension Displays 14
1.3.1 Overview of 3D Technology 14
1.3.2 Stereoscopic Displays 15
1.3.3 Emission Driving Scheme 17
1.4 Motivation 18
Chapter 2 AMOLED driving 20
2.1 Driving Device 20
2.1.1 ɑ-Si TFT 20
2.1.2 LTPS TFT 21
2.1.3 ɑ -IGZO TFT 21
2.2 AIM-SPICE and Device Model 22
2.3 Compensating Methods for AMOLED 24
2.3.1 Threshold Voltage 26
2.3.2 Mobility 28
2.3.3 Voltage Drop 29
2.3.4 OLED Lifetime 30
2.3.5 Aperture Ratio 32
Chapter 3. A Novel Voltage-programming Circuit with Electrical Characteristics of ɑ-IGZO TFTs and non-uniformity of the OLED Luminance 35
3.1 Introduction 35
3.2 Circuit Schematic and Operation 36
3.3 Simulation Results and Discussion 42
3.4 Summary 51
Chapter 4. A a-IGZO TFT Pixel Circuit Using Novel Mobility Compensated Method In AMOLEDs 53
4.1 Introduction 53
4.2 Circuit Schematic and Operation 54
4.3 Simulation Results and Discussion 61
4.4 Summary 66
Chapter 5. Conclusions and Future Work 68
5.1 Conclusion 68
5.2 Future Work 69
References 70

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