極化並成串粒子懸浮液之反射率與穿透率操控應用於電子紙顯示器

Abstract

電子紙為顯示器技術中一個新興的領域，在此我們提出一個粒子極化技術，利用彩色粒子懸浮液在電場下被極化成微粒串的過程達到顯示介質之反射率以及穿透率的大幅改變。藉由施加特殊頻率的外加電場，原本散布在溶液中的粒子會被極化並產生誘導偶極矩，而在均勻電場下，具有同方向之誘導偶極矩的粒子則會互相吸引並且形成平行電場方向之粒子串。在論文中我們研究了粒子在電場下極化成串的現象並提出未來可能商品化的模型以及專利；同時我們也展示了粒子成串的實驗結果以及在5x5矩陣電極與可撓式基板上驗證電子紙顯示器的可行性。在顯微鏡觀察以及反射率量測中，我們發現聚苯乙烯粒子懸浮液可以被均勻的交流電場所驅動，在我們施加了500 kHz, 0.574MVm-1的均勻電場時，其電場造成穿透率以及反射率在625毫秒(第一個量測點)內上升為起始值的兩倍，即對比為2:1，並且在反射率穩定之後達到最高10:1的對比度(23.7秒)。藉由彩色粒子的使用或是核-殼粒子的設計與合成，未來我們有機會可以達到一個彩色以及具有極短反應時間的電子紙顯示器。

Electronic paper display is an emerging area of the display technology. Here we proposed an electronic paper technology by polarizing and chaining the dyed particle suspensions. The particle chains formation results in the dramatic optical change of the display medium in both transmittance and reflectance. By applying electric field at a specific frequency range, suspended particles would be polarized and induced to have specific dipole moments. The electrically-polarized particles attract each other and form particle chains in the uniform electric field. Here we investigated the phenomena of particle-chain transformation, and proposed the possible commercialized models and patents. We also showed the experimental results of particle chains formation, the feasibility of realizing an electronic paper display on a 5x5 pixel array or a flexible substrate, and an optical component of a particle suspension droplet on a microfluidic platform. In the in situ observation and the reflectance measurements, we found that the polystyrene particle suspensions would be driven when we applied a uniform electric field of 500 kHz, 0.574 MVm-1. The electric field caused the reflectance change to twice of the initial value in 625 ms (the first data point) and the contrast ratio was 2:1. The reflectance was stabled in 23.7 s and reached a contrast ratio of 10:1 in a uniform AC electric field. By implementing the color particles or the synthesis of the core-shell particles, we would be able to achieve a color electronic paper display with a short response time.