기하 광학적 광선 추적법을 이용한 LED 전구의 무지향성 배광설계

Abstract

LEDs (Light Emitting Diodes) present many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching. As LED materials technology grew more advanced, light output rose, while maintaining efficiency and reliability at acceptable levels. Recently, with the prohibition of the sale of incandescent light bulbs, thus encouraging the use of more energy-efficient lighting alternatives, LEDs were commonly used as replacements for incandescent. Although LED has many advantages, it is difficult to directly replace the incandescent light bulbs with LED bulbs because of difference of light distribution pattern between LED and incandescent light bulbs. LED bulbs naturally distribute light in a directional manner out the top and side of the lens while incandescent light bulbs emit light in all directions as omnidirectional sources. So, simply replacement from incandescent light bulbs to LED bulbs in existing lighting system is resulted in decrease of uniformity ratio of illumination. Therefore, it is required to develop LED bulbs with omnidirectional light distribution pattern to replace incandescent light bulbs without extra cost such as purchase of additional diffuser and reflector. There are few commercialized LED bulbs with omnidirectional light distribution pattern with complicated design. In this work, we designed the LED bulbs with omnidirectional light distribution pattern by optical design which is sufficient with regulation from Energy Star. Especially, we simply modified the shape and transmittance/reflectance of glove to optimize the omnidirectional light distribution pattern. Then, we fabricated the prototype of LED bulbs. Finally, we found that our LED bulbs can meet the regulation for omnidirectional light distribution pattern defined by Energy Star. This works shows that it is possible to fabricated the low-cost LED bulbs with omnidirectional light distribution pattern without extra cost such as complicated design.