現今薄膜電晶體技術廣泛地整合於主動式矩陣液晶顯示器中以降低面板之製造成本，而在諸多薄膜電晶體技術中，以非晶相銦鎵鋅氧化物、氫化非晶矽與低溫多晶矽為應用之主流。非晶相銦鎵鋅氧化物薄膜電晶體因有著高均勻性與高載子移動率之優勢使其適用於大尺寸之液晶顯示器。而氫化非晶矽薄膜電晶體之載子移動率雖然較低，但其也具有高均勻性，且此製程所需的製造成本較低並擁有高感光度之特性，使得氫化非晶矽薄膜電晶體於大尺寸光學式互動面板之應用中受到青睞。另一方面，由於低溫多晶矽薄膜電晶體之載子移動率高於上述兩種製程，因此將其整合於閘極驅動電路可使電路擁有高驅動能力，以改善高解析度面板掃描線負載加大使掃描訊號產生延遲之問題。
本論文提出一個非晶相銦鎵鋅氧化物之藍相液晶畫素電路、一個氫化非晶矽之光感測畫素電路與兩個低溫多晶矽之閘極驅動電路，並藉由量測及模擬結果驗證電路之可行性。第一個電路為非晶相銦鎵鋅氧化物之畫素電路，此電路由四顆薄膜電晶體與兩顆電容所組成，其應用於大尺寸之藍相液晶顯示器，特色為採用電容耦合方式抬升液晶之跨壓，以達到藍相液晶最大穿透度之操作電壓，並使用預充電方式降低資料寫入階段液晶充放電之電壓範圍，以避免資料電壓無法正確寫入。此電路根據掃描頻率180 Hz Full HD顯示器之規格進行模擬，結果顯示此電路可在資料電壓供給0 V至15 V範圍下，可產生-0.19 V至29.58 V之液晶跨壓範圍，達到藍相液晶最大穿透度之操作電壓，以增加藍相液晶應用於現行顯示器系統之可行性。第二個電路為氫化非晶矽之光感測畫素電路，其適用於大尺寸光學式互動面板，此電路利用氫化非晶矽薄膜電晶體高感光度之特性，結合RGB彩色濾光片使其可獨立感測三原色之光源，並藉由一補償電路架構與一主動式負載，以分別減緩環境光與影像光源之反射光對光感測畫素電路之干擾。量測結果顯示在12560 lux之環境光與588 lux之模擬反射光照射下，此電路仍可正確偵測有/無輸入光源照射，使光學式互動面板可應用於高環境光之環境，且不受影像光源反射干擾增加其可靠度。第三個電路為低溫多晶矽之閘極驅動電路，此電路由十二顆薄膜電晶體與三顆電容所組成，其應用於高解析度液晶顯示器，藉由產生一較高電位之內部訊號以驅動輸入薄膜電晶體，使其於輸入電壓階段操作於線性區，因此輸入電壓可以完整地傳送至驅動薄膜電晶體之閘極端，而不會受輸入薄膜電晶體之臨界電壓影響，此外採用電容疊接架構提高驅動薄膜電晶體之閘極電壓，以增加其驅動能力進而對輸出點進行快速放電。模擬結果顯示此電路可產生一致的輸出波形，且輸出波形之下降時間與傳統閘極驅動電路相比改善幅度可達到11.79 %。第四個電路亦為應用於高解析度液晶顯示器之低溫多晶矽閘極驅動電路，由十二顆薄膜電晶體與兩顆電容所組成，此電路採用一較高電位之定電壓源，不僅產生用於增強輸入薄膜電晶體驅動能力之內部訊號，也搭配一儲存電容抬升驅動薄膜電晶體之閘極電壓以增強其驅動能力，因此電路可達到縮短輸出波形下降時間之功能。模擬結果顯示輸出波形之下降時間與傳統閘極驅動電路相比改善幅度可達到11.69 %，且在薄膜電晶體臨界電壓變異±1.5 V範圍內，電路輸出波形之下降時間不受其影響，此外根據量測結果驗證電路在一畫面時間內可產生連續且穩定的輸出波形。上述第三及第四個閘極驅動電路，皆可在不增加電晶體尺寸下即縮短輸出波形下降時間，以達到高解析度顯示器嚴峻的規格要求，進一步提升顯示器之畫面品質。

SUMMARY

This thesis proposes one blue-phase liquid-crystal (BPLC) pixel circuit, one optical pixel sensor circuit, and two gate driver circuits. The BPLC pixel circuit based on amorphous indium-gallium-zinc oxide thin-film transistor (a-IGZO TFT) utilizes capacitive coupling method to boost the voltage which is across the BPLC, and adopts pre-charge method to prevent that the distort data voltage is applied to BPLC. In addition, owing to the high photo-sensitivity of hydrogenated amorphous silicon (a-Si:H) TFT, the proposed optical pixel sensor circuit incorporates a-Si:H TFT with RGB color filters to sense optical signals from one of the three primary colors. Moreover, The circuit uses a compensating circuit structure and a designed active load to achieve high immunity of ambient light and reflected light. Besides, as the resolution of display rises, the data input time of one row is significantly shortened, so the switching TFTs of pixel have to be accurately closed to avoid the distorted data voltage. This thesis presents two gate driver circuits based on low temperature poly-silicon (LTPS) TFT, both circuits generate high voltage level internal signal to drive input TFTs to prevent that the threshold voltage of input TFTs degrades the input voltage. Furthermore, the proposed gate driver circuits improve the gate voltage of driving TFT to enhance the driving capability of driving TFT, shortening the falling time of output waveforms.

[1] U. B. Kang and Y. H. Kim, “A new COG technique using low temperature solder bumps for LCD driver IC packaging applications,” IEEE Trans. Comp. package. Technol., vol. 27, no. 2, pp. 253–258, Jan. 2004.
[2] H. Kristiansen and J. Liu, “Overview of conductive adhesive interconnection technologies for LCD’s,” IEEE Trans. Comp., Packag., Manufact. Technol. A, vol. 21, no. 2, pp. 208–214, Jan. 1998.
[3] H. Lee, H. J. Park, O. J. kwon, S. J. Yun, J. H. Park, S. Hong, and S. T. Shin, “The world's first blue phase liquid crystal display,” in SID Symp. Dig. Tech. Papers, vol. 42, no. 1, pp 121–124, Jun. 2011.
[4] L. Rao, Z. Ge, S. T. Wu, and S. H. Lee, “Low voltage blue-phase liquid crystal displays,” Appl. Phys. Lett., vol. 95, no. 23, p. 231101, Dec. 2009.
[5] H. C. Cheng, J. Yan, T. Ishinabe, and S. T. Wu, “Vertical field switching for blue-phase liquid crystal devices,” Appl. Phys. Lett., vol. 98, no. 26, p. 261102, Jun. 2011.
[6] M. Kim, M. S. Kim, B. G. Kang, M. K. Kim, S. Yoon, S. H. Lee, Z. Ge, L. Rao, S. Gauza, and S. T. Wu, “Wall-shaped electrodes for reducing the operation voltage of polymer-stabilized blue phase liquid crystal displays,” J. Phys. D, Appl. Phys., vol. 42, no. 23, p. 235502, Dec. 2009.
[7] M. Jiao, Y. Li, and S. T. Wu, “Low voltage and high transmittance blue-phase liquid crystal displays with corrugated electrodes,” Appl. Phys. Lett., vol. 96, no. 1, p. 011102, Jan. 2010.
[8] L. Rao, H. C. Cheng, and S. T. Wu, “Low voltage blue-phase LCDs with double-penetrating fringe fields,” J. Display Technol., vol. 6, no. 8, pp. 287–289, Aug. 2010.
[9] L. Rao, J. Yan, S. T. Wu, S. I. Yamamoto, and Y Haseba, “A large kerr constant polymer-stabilized blue phase liquid crystal,” Appl. Phys. Lett., vol. 98, no. 8, p. 081109, Feb. 2011.
[10] Y. Chen, D. Xu, S. T. Wu, S. Yamamoto, and Y. Haseba, “A low voltage and submilliesecond-response polymer-stabilized blue phase liquid crystal,” Appl. Phys. Lett., vol. 102, no. 14, p.141116, Apr. 2013.
[11] C. D. Tu, C. L. Lin, J. Yan, Y. Chen, P. C. Lai, and S. T. Wu, “Driving scheme using bootstrapping method for blue-phase LCDs,” J. Display Technol., vol. 9, no. 1, pp. 3–6, Jan. 2013.
[12] C. L. Lin, C. D. Tu, M. H. Cheng, C. C. Hung, C. H. Lin, and N. Sugiura, “Novel dual-coupling pixel circuit to achieve high transmittance of blue-phase liquid crystal,” IEEE Electron Device Lett., vol. 36, no. 4, pp. 354–356, Apr. 2015.
[13] C. L. Lin, M. H. Cheng, C. D. Tu, P. C. Lai, and P. C. Lai, “Design of pixel circuits for blue-phase liquid crystal displays,” J. Display Technol., vol. 12, no. 2, pp. 153–157, Feb. 2016.
[14] K. S. Nam and O. K. Kwon, “A highly power-efficient LED backlight driving system for LCD TVs,” IEEE Trans. Consum. Electron., vol. 58, no. 2, pp. 264–268, May 2012.
[15] C. H. Chen, C. H. Ting, and Y. P. Huang, “3D interactive system using integral photography by embedded optical sensors for portable devices,” J. Display Technol., vol. 12, no. 11, pp. 1329–1334, Aug. 2016.
[16] M. Yamaguchi, Y. Kaneko, and K. Tsutsui, “Two-dimensional contact type image sensor using amorphous silicon photo-transistor,” Jpn. J. Appl. Phys., vol. 32, no. 1, pp. 458–461, Jan. 1993.
[17] M. J. Powell, “The physics of amorphous-silicon thin-film transistors,” IEEE Trans. Electron Devices, vol. 36, no. 12, pp. 2753–2763, Dec. 1989.
[18] C. L. Lin, M. H. Cheng, C. D. Tu, C. E. Wu, and F. H. Chen, “Low-power a-Si:H gate driver circuit with threshold-voltage-shift recovery and synchronously controlled pull-down scheme,” IEEE Trans. Electron Devices, vol. 62, no. 1, pp. 136–142, Jan. 2015.
[19] S. C. Huang, W. H. Hsu, P. C. P. Chao, and C. H. Tsai, “A new active 3D optical proximity sensor array and its readout circuit,” IEEE Sensors Journal, vol. 14, no. 7, pp. 2185–2192, Jul. 2014.
[20] M. H. Izadi, O. Tousignant, M. F. Mokam, and K. S. Karim, “An a-Si active pixel sensor (APS) array for medical X-ray imaging,” IEEE Trans. Electron Devices, vol. 57, no. 11, pp. 3020–3026, Nov. 2010.
[21] C. Brown, H. Kato, K. Maeda, and B. Hadwen, “A continuous-grain silicon-system LCD with optical input function,” IEEE J. Solid-State Circuits, vol. 42, no. 12, pp. 2904–2912, Dec. 2007.
[22] A. Ablieah, W. den Boer, T. Larsson, T. Baker, S. Robinson, R. Siegel, N. Fickenscher, B. Leback, T. Griffin, and P. Green, “Integrated optical touch panel in a 14.1” AMLCD,” in SID Symp. Dig. Tech. Papers, vol. 35, no. 1, pp. 1544–1547, May 2004.
[23] C. L. Lin, C. E. Wu, P. S. Chen, C. H. Chang, C. C. Hsu, J. S. Yu, C. Chang, and Y. H. Tseng, “Hydrogenated amorphous silicon thin-film transistor-based optical pixel sensor with high sensitivity under ambient illumination,” IEEE Electron Device Lett., vol. 37, no. 11, pp. 1446–1449, Nov. 2016.
[24] C. L. Lin, C. E. Wu, P. S. Chen, P. C. Lai, J. S. Yu, C. Chang, and Y. H. Tseng, “Optical pixel sensor of hydrogenated amorphous silicon thin-film transistor free of variations in ambient illumination,” IEEE J. Solid-State Circuits, vol. 51, no. 11, pp. 2777–2785, Nov. 2016.
[25] C. P. Kung, W. J. Chiang, Y. J. Chen, P. H. Wang, M. H. Wang, J. C. Ho, and C. C. Lee, “Novel flexible photo sensing pixel for large size electrophoretic display with pen writing function,” in SID Symp. Dig. Tech. Papers, vol. 42, no. 1, pp. 1822–1825, Jun. 2011.
[26] W. J. Nam, H. J. Lee, H. S. Shin, S. G. Park, and M. K. Han, “Low-voltage driven P-type polycrystalline silicon thin-film transistor integrated gate driver circuits for low-cost chip-on-glass panel,” Jpn. J. Appl. Phys., vol. 45, no. 5B, pp. 4389–4391, May 2006.
[27] C. L. Lin, F. H. Chen, W. C. Ciou, Y. W. Du, C. E. Wu, and C. E. Lee, “Simplified gate driver circuit for high-resolution and narrow-bezel thin-film transistor liquid crystal display applications,” IEEE Electron Device Lett., vol. 36, no. 8, pp. 808–810, Jun. 2015.
[28] C. L. Lin, C. E. Wu, F. H. Chen, P. C. Lai, and M. H. Cheng, “Highly reliable bidirectional a-InGaZnO thin-film transistor gate driver circuit for high-resolution displays,” IEEE Trans. Electron Devices, vol. 63, no. 6, pp. 2405–2411, Jun. 2016.
[29] D. S. Kim and O. K. Kwon, “A small-area and low-power scan driver using a coplanar a-IGZO thin-film transistor with a dual-gate for liquid crystal displays,” IEEE Electron Device Lett., vol. 38, no. 2, pp. 195–198, Feb. 2017.
[30] M. Nakamizo, M. Yonemaru, Y. Iwase, and T. Fukaya, “A low power consumption and high reliability architecture for a-Si TFT gate driver on glass,” in SID Symp. Dig. Tech. Papers, vol. 41, no. 1, pp 28–31, May 2010.
[31] B. Kim, S. C. Choi, S. H. Kuk, Y. H. Jang, K. S. Park, C. D. Kim, and M. K. Han, ”A novel level shifter employing IGZO TFT,” IEEE Electron Device Lett., vol. 32, no. 2, pp. 167–169, Feb. 2011.
[32] S. J. Yoo, S. J. Hong, J. S. Kang, H. J. In, and O. K. Kwon, “A low-power single-clock-driven scan driver using depletion-mode a-IGZO TFTs,” IEEE Electron Device Lett., vol. 33, no. 3, pp. 402–404, Mar. 2012.
[33] W. Benzarti, F. Plais, A. D. Luca, and D. Pribat, “Compact analytical physical-based model of LTPS TFT for active matrix displays addressing circuits simulation and design,” IEEE Trans. Electron Devices, vol. 51, no. 3, pp. 345–350, Mar. 2004.
[34] J. W. Choi, J. I. Kim, S. H. Kim, and J. Jang, “Highly reliable amorphous silicon gate driver using stable center-offset thin-film transistors,” IEEE Trans. Electron Devices, vol. 57, no. 9, pp. 2330–2334, Sep. 2010.
[35] C. L. Lin, C. D. Tu, M. C. Chuang, and J. S. Yu, “Design of bidirectional and highly stable integrated hydrogenated amorphous silicon gate driver circuits,” J. Display Technol., vol. 7, no. 1, pp. 10–18, Jan. 2011.
[36] J. E. Pi, M. K. Ryu, C. S. Hwang, S. H. Yang, S. H. K. Park, S. M. Yoon, H. K. Leem, Y. K. Kim, J. D. Kim, H. S. Oh, and K. C. Park, “A low-power scan driver circuit for oxide TFTs,” IEEE Electron Device Lett., vol. 33, no. 8, pp. 1144–1146, Aug. 2012.
[37] W. J. Wu, L. R. Zhang, Z. P. Xu, L. Zhou, H. Tao, J. H. Zou, M. Xu, L. Wang, and J. B. Peng, “A high-reliability gate driver integrated in flexible AMOLED display by IZO TFTs,” IEEE Trans. Electron Devices, vol. 64, no. 5, pp. 1991–1996, May 2017.