- 學位論文
提升micro LED正向輝度與抗反射之二次光學結構設計
Secondary optical structure with anti-reflection design to improve micro LED normal luminance
摘要
μLED顯示器基於其小體積與高發光強度之發光元件，有潛力成為OLED後的下一代顯示器之發光元件。但在封裝後μLED大角度出光容易在交界面產生全反射，且μLED側向出光無法有效的利用，使光的利用效率大幅降低。本文將針對此問題，利用LightTools®幾何光學模擬軟體進行二次光學設計，解決封裝後μLED正向輝度降低40%之問題。首先在μLED旁加入上方被黑矩陣覆蓋之低折射率介質反射杯降低側向出光，上方搭配高折射率的OCA及低折射率的倒梯形結構將光線偏折到正向，減少大角度出光，提升正向輝度。理想狀態下，此設計最高可提升至少10%之正向輝度。 由於介質反射杯上方有黑矩陣覆蓋，除了可降低側向出光，還可減少至少50%之環境反射光。但實際製作時可能會產生誤差，本文針對μLED製作時可能產生之誤差，如轉置誤差與倒梯形對組誤差進行探討，確認在有誤差的時候依然可提升正向輝度。最後驗證不同視角下是否會有色偏產生，證實二次光學結構之Δu'v'，在不同視角下最大值僅有0.03，人眼不易分辨出差異。
並列摘要
μLED have high potential to become the source of display due to its high luminance and tiny volume. But after packaging, light extraction efficiency will decrease due to side emission and total reflection at glass/air surface. In this paper, we designed a secondary optical system which composed of reflector and inverted trapezoid to decrease luminance loss caused by packaging, and current loss was 40%. The reflector was made from low refractive index material, covered by black matrix, and placed around μLED. Above the μLED was an inverted trapezoid with low refractive index, and it was placed inside OCA with high refractive index. All results were simulated by LightTools®. For ideal case, luminance increased by 10% at least after adding systems. Furthermore, reflector could also decrease reflectance for more than 50% due to black matrixes. Transfer displacement error of μLED and alignment error of inverted trapezoid were also considered. For worst case, luminance could decrease for 15% after packaging, which could be accepted. At last, we checked color difference under different viewing angle. After adding secondary optical system,Δu'v' could be lower than 0.03 under different viewing angle, which was hard to be noticed by human eye.