| 摘要: | 傳統焦電型紅外線感測器廣泛應用於智慧家居與物聯網，但其感測範圍受限，最大半角僅約50度，難以突破60度。這是由於大角度收光會受到菲涅爾效應、漸暈效應及餘弦四次方定理的影響，導致光能量下降及有效光學孔徑縮小，進而限制了感測器的性能。本研究提出一種應用於焦電型紅外線感測器之大角度收光的反射型類稜型結構，解決大角度區域感測死角，結合多焦點複合型菲涅爾透鏡，實現感測範圍的大幅提升。
反射型類稜型結構透過將大角度入射的感測光訊號轉化為小角度入射，有效降低菲涅爾效應及漸暈效應的影響，有別於傳統結構，利用全反射面使光訊號至少發生一次反射，實現大角度偏折，將感測範圍擴展至半角60度以上，甚至超過90度。材料選用高密度聚乙烯為材料，根據菲涅爾方程組計算光學行為，並設計通用類稜型結構參數。通過自建Python程式模擬，結果顯示最佳設計可將結構光通效率提升至50%以上，滿足焦電元件偵測人體的最低能量需求。
本研究克服傳統焦電型紅外線感測器無法大角度收光的限制，擴大感測範圍、減少感測死角，提升靈敏度，為智慧家居與物聯網提供高效的創新解決方案。
;Traditional pyroelectric infrared sensors (PIR sensors) are widely used in smart home and Internet of Things (IoT) applications. However, their sensing range is limited, with a maximum half-angle of approximately 50 degrees, rarely exceeding 60 degrees. This limitation arises due to the effects of the Fresnel phenomenon, vignetting effect, and the cosine fourth-power law, which cause a reduction in light energy and effective optical aperture, thereby constraining sensor performance. This study proposes a reflective prismatic-like structure for large-angle light collection in PIR sensors, addressing sensing blind spots in wide-angle regions. By integrating a multi-focus compound Fresnel lens, the sensing range is significantly enhanced.
The reflective prismatic-like structure converts large-angle incident sensing light signals into small-angle incident light, effectively mitigating the influence of Fresnel losses and vignetting. Unlike conventional designs, it utilizes a total reflection surface, ensuring that light signals undergo at least one reflection, enabling large-angle deflection. This extends the sensing range beyond a half-angle of 60 degrees, and even surpasses 90 degrees. The structure is fabricated using high-density polyethylene (HDPE) as the primary material. Optical behavior is calculated based on Fresnel equations, and universal prismatic-like structural parameters are designed accordingly. Simulations conducted using a custom Python program demonstrate that the optimal design improves the structure’s optical efficiency to over 50%, meeting the minimum energy requirements for pyroelectric elements to detect human bodies.
This study overcomes the limitations of traditional PIR sensors in large-angle light collection, extending the sensing range, reducing blind spots, and enhancing sensitivity. It offers an innovative and efficient solution for smart home and IoT applications. |
