四階堆疊電極於負型液晶垂直配向邊緣場效驅動之設計

Abstract

隨著顯示技術邁向高效率、低功耗發展，液晶顯示器對穿透率、操作電壓與反應時間的要求日益提高。負型液晶垂直配向邊緣場效驅動(VA-FFS)模式雖具良好視角與反應特性，然而傳統3D VA-FFS結構在長時間驅動下，雖能維持良好的穩定性，但其光學穿透率仍偏低，限制其應用效能。 為提升穿透率表現，有研究在3D VA-FFS結構上方引入整片共用電極的3D VA-FFS COM結構，可有效提升穿透率並降低操作電壓，惟此架構於小電極間隙的長時間電壓驅動下會發生嚴重的兩步驟轉動現象，穩定度不佳，且為達到高穿透率，仍需略高的操作電壓，限制其在低功耗應用中的可行性。 為解決上述問題，本研究提出創新之四階堆疊電極結構(4-levlel stacked electrode)。此架構透過堆疊的雙層畫素電極，並且各電極不同輸出電壓，於液晶層中形成多向電場，使液晶分子得以因高壓差而快轉動，在保持低操作電壓的同時，也避免小尺寸電極間隙下不穩定的情況，達到高穿透率與穩定性。 此外，本研究亦導入交錯式結構設計與下層電極尺寸優化，使液晶排列更佳均勻，所提出之交錯式4-level結構在3V操作電壓下即能達成接近90%之穿透率，且回復時間可降低至2ms，展現出優秀的反應時間與穿透率表現。 綜合而言，本研究所提出之四階堆疊電極設計，兼具高穿透率、低操作電壓與穩定液晶響應的優勢，克服VA-FFS COM在穩定性與效能上的限制，為未來高效能液晶顯示器開發提供具潛力之創新電極結構。

As display technology advances toward higher efficiency and lower power consumption, the performance requirements for liquid crystal displays (LCDs) in terms of transmittance, operate voltage, and response time have become increasingly stringent. Although the vertically-aligned fringe-field switching (VA-FFS) mode using negative liquid crystals provides wide viewing angles and favorable response characteristics, the conventional 3D VA-FFS structure still suffers from low optical transmittance under extended driving durations, despite maintaining good stability. To improve transmittance, previous studies have introduced the 3D VA-FFS COM structure by adding a continuous top common electrode. While this design effectively enhances transmittance and reduces operate voltage, it exhibits severe two-step rotation phenomena and poor stability long-term voltage drive with small electrode gaps. Moreover, achieving high transmittance in this structure still requires a relatively higher operate voltage, which limits its feasibility in low-power applications. To address these issues, this study proposes an innovative 4-level stacked electrode structure. This design features dual-layer pixel electrodes stacked vertically, each driven by different voltages, generating multi-directional electric fields within the liquid crystal layer. The resulting high field gradient enables rapid molecular rotation while maintaining a low operate voltage, thereby suppressing instability in narrow-gap electrodes and achieving both high transmittance and structural stability. Furthermore, a staggered structural design along with optimization of the lower electrode dimensions is implemented in this study to improve the uniformity of liquid crystal orientation. The proposed interlaced 4-level structure achieves nearly 90% transmittance at an operate voltage of 3V, with response time reduced to as low as 2 milliseconds, demonstrating excellent optical and dynamic performance. In summary, the 4-level stacked electrode design developed in this study offers high transmittance, low operate voltage, and stable liquid crystal response, effectively overcoming the limitations of VA-FFS COM structures in terms of performance and stability. It provides a promising structural innovation for future development of high-efficiency LCDs.