全周型LED球泡燈二次光學之設計

Abstract

目前常見的LED球泡燈，受限於LED平面發光的特性，把LED以平面排列組裝在半圓球罩中，點亮後的發光角度會在180度以內，無法符合能源之星規範定義的球泡燈的全周型光形。為了改善目前常見球泡燈的光形，本文提出採用二次光學的全反射透鏡(TIR lens)，把平面發光的LED光形，透過特殊的TIR lens導光以改變光形，得到滿足能源之星的全周型光形規範。本文先從LED球泡燈的發展現況進行整理，接著搜尋相關大角度的透鏡專利，提出不同於相關專利的TIR透鏡的外形，再規劃光學模擬的設計流程，設計出有別於現有專利的新型全周型二次光學透鏡，接著以CNC製作透鏡樣品，把透鏡樣品與其他球泡燈零件組裝成球泡燈成品，量測燈具的遠場光形，量測結果的遠場光形接近全周型標準，發光角度範圍達到280度、135度至180度之間流明值為總流明的6%以上，而135度至-135度之間的光強分佈有超過一半的量測點符合全周型的均勻度標準規範，其餘量測點則落在規範的邊緣，實際量測結果與模擬結果的差異相近，與現有市面上的LED球泡燈比較，本文LED球泡燈的優點是具有更大的發光角度範圍、能夠照亮球泡燈下方的區域。

The common LED lamps presented in the commercial retailers generally emitter the ray in the 180 degree range. The light distribution is produced from that LEDs with planar emitting characteristic are placed inside a semi-sphere cover. This distributional angle that is less than 180 degree can not meet the standard of an omni-directional lamp of Energy Star specification .In order to improve the light distribution of the previous mentioned LED lamps, this thesis proposed using a secondary optics lens, total internal reflection (TIR) lens, to change LED light distribution. Throughout the technique of TIR lens, light can be guided forward specific directions that can meet Energy Star specification. This thesis began with the current state of development of the LED lamp. Then we searched relative lens patents about large angle applications. Compared with these patents, we proposed a specific TIR lens profile different from the searched patents. Based the TIR lens profile, we revised the TIR lens profile by optics simulation analysis until the light distribution met the standard of omni-directional lamp. The designed model was sent to a CNC factory to manufacture a plastic mock-up sample. We assembled the mock-up lens and the other parts for a LED lamp. The LED lamp was measured by a goniophotometer device. The measured result of the far-filed light distribution is approximate to the standard of omni-directional lamp. The active beam angle reaches 280 degree. The lumen between 135 and 180 degree is more than 6 percent of the total lumen. The measured points between 135 and -135 degree are more than half that satisfy the required uniformity of the standard of omni-directional lamp. The others are slight out of the range of standard. The difference between simulation result and measured one is close. Compared with the LED lamp presented in commercial retailers, the LED lamp designed in the thesis has the advantage of larger beam angle that can light the area below a LED lamp.