以微陣列結構提升Micro-LED出光效率之低反射二次光學設計

Abstract

作為一種新的顯示技術，Micro-LED顯示技術主要基於第三代半導體材料氮化鎵（GaN），其獨特的優勢，如低功耗、高對比、快速響應和高可靠性，已經引起了行業和學術界的廣泛關注。然而隨LED的體積縮小，內部Internal Quantum Efficiency(IQE)降低導致裸晶出光強度降低，以及大角度出光會造成出光不易被人眼接收，因此，如何有效地收集大角度出光並加以利用成為一個值得思考的課題。本文是透過LightTools®進行幾何光學模擬及分析開發出一種具反射杯及黑矩陣之二次光學結構設計，以提升Micro-LED之效率。 透過反射杯及倒梯形結構建構出六角形出光光路為核心思想，將Micro-LED出光的光路及環境光吸收的光路分開，並儘量收斂出光光路。這樣一來，可以降低吸光光路及出光光路的相互影響，並分別加以優化。再者，當出光光路越發收斂，環境光吸光光路就能夠佔據更大的面積，進一步吸收更多環境光以提升面板的對比度。經過二次光學設計之後可以從原先具有40%的出光損耗下降至4.54%，環境光反射從25%下降至4.92%。

As a novel display technology, Micro-LED display technology is primarily based on third-generation semiconductor material, gallium nitride (GaN). Its unique advantages, including low power consumption, high brightness, rapid response, and high reliability, have garnered widespread attention from both industry and academia. However, as LEDs shrink in size, the reduction in Internal Quantum Efficiency (IQE) leads to decreased light emission intensity, and an increase in lateral light emission results in some light being less easily perceived by the human eye. Therefore, effectively collecting and utilizing laterally emitted light becomes an important consideration. In this paper, we utilize LightTools® for geometric optical simulations and analysis to develop a secondary optical structure with reflector cups and a black matrix. This design addresses the previously mentioned issues of increased lateral light emission and enhances the utilization of Micro-LED light output. The core concept involves constructing a hexagonal light path by using reflector cups and trapezoidal structures, separating the Micro-LED light path from the light path absorbed by the environment and converging the light paths as much as possible. This approach reduces the mutual interference between the light-absorbing path and the light-emitting path and optimizes them separately. Furthermore, as the light-emitting path converges further, the light-absorbing path for environmental light can occupy a larger area, further enhancing the panel's contrast. After the secondary optical design, the light loss, which was initially at 40%, has been reduced to 4.54%, and environmental light reflection has decreased from 25% to 4.92%.