具環境感知能力的彩色電子紙前光調控

Abstract

本研究旨在針對電泳式顯示器，改良現有之前光模組，結合環境光感測器以獲取環境光資訊，達成自動調整前光亮度以及色溫，並且針對顯示影像作色溫之補償以校正色偏。為達成上述目標，本研究建置一套嵌入式系統方法：採用發光二極體及導光板之前光架構與低功耗微控制器，搭配經校正之環境光感測器，先以對數域回歸估測照度，與透過係數最佳化等方式估測環境相對色溫；再依照照度分段策略與倒數色溫線性混光原理，並以查表方式連續調節前光亮度與色溫；同時在影像處理流程中，以固定參考白點實作色適應轉換以進行白點對應與色溫補償；最後以標準色卡、照度計與分光式色度計進行系統校正與驗證。實驗結果顯示，本系統可於多種環境光源下維持彩色電子紙的亮度、色溫與色域一致性，為未來低功耗、彩色顯示電子書閱讀器提供高可行性的硬體整合方案。

This study aims to improve the existing front-light module for electrophoretic displays by integrating an ambient light sensor to obtain environmental lighting information, enabling automatic adjustment of front-light brightness and correlated color temperature (CCT), as well as compensating the display image’s color temperature to correct color shifts. To achieve these objectives, an embedded system approach was developed, employing a front-light architecture composed of light-emitting diodes and a light guide plate, together with a low-power microcontroller and a calibrated ambient light sensor. Illuminance was estimated via logarithmic-domain regression, while ambient correlated color temperature was determined through coefficient optimization. A segmented illuminance strategy combined with the inverse color temperature linear mixing principle was adopted, and front-light brightness and CCT were continuously adjusted using a lookup table method. In the image processing pipeline, a fixed reference white point was applied to implement chromatic adaptation for white point mapping and color temperature compensation. System calibration and validation were conducted using a standard color chart, an illuminance meter, and a spectroradiometer. Experimental results show that the proposed system can maintain consistent brightness, color temperature, and color gamut of a color electronic paper display under various ambient light sources, providing a highly feasible hardware integration solution for future low-power, color-display e-book readers.