New Physics: Sae Mulli (새물리)

Korean Physical Society (한국물리학회)
권호 표지
DOI QR코드

DOI QR Code

Simulation Study on the Optical Performances of LED Flat Illumination Devices Based on Remote Phosphor Designs

분리형 형광체 구조를 이용한 LED 평판 조명의 광학특성에 대한 시뮬레이션 연구

  • 이병우 (한림대학교 전자물리학과) ;
  • 고재현 (한림대학교 전자물리학과)
  • Published : 2012.01.31
⟨ Previous Next ⟩

Abstract

Systematic comparisons between PC(phosphor-coated)-LED-based and RP(remote-phosphor)- LED-based illumination devices have been carried out by using optical simulations based on the Monte-Carlo ray-tracing technique. In order to simulate the phosphor particles reliably, we determined the absorption and the excitation spectra of phosphors based on the measured emission spectrum and analysis. The device efficiencies of the RP-LED-based devices were higher than those of the PC-LED-based devices by 4~10 %. The illumination efficiencies of the RP-LED-based devices were higher than those of the PC-LED-based devices by 8~11.6 %. These results contributed to the higher illuminances on the illuminated surfaces at a distance of 1 m from the devices. The origin of these higher efficiencies of the RP-LBE-based devices was attributed to the reduced probability of the absorption in the RP-LED-based illumination devices of the light generated by LED. The differences in the color coordinates between the center and other locations on the illuminated surface were found to be less than 0.01 except for the directly-lit RP-LED-based device, which exhibited a color difference of about 0.04. The color mixing occurred in only the phosphor layer in the directly-lit RP-LED-based device while for other LED devices, it occurred not only in the phosphor layer but also in the alabaster glass plate, resulting in better color uniformity.

광선 추적 시뮬레이션에 기반해서 청색 고체발광다이오드(LED)와 형광체층이 분리된 구조의 LED 조명의 특성을 백색 LED 조명의 그것과 비교하였다. 분리형 형광체 구조가 적용된 한 가지 종류의 직하형 조명 및 두 가지 종류의 엣지형 평판 조명은 모두 백색LED조명에 비해 높은 기구효율과 조명효율을 나타내었다. 이는 LED 칩과 형광체 층이 공간적으로 분리됨으로써 형광체에서 스토크스 전이에 의해 방출된 장파장의 빛이 LED 칩에 의해 재흡수될 확률이 줄어들었기 때문이다. LED 조명으로부터 1 m 떨어져 있는 조광면에서의 색좌표 편차는 분리형 형광체가 적용된 직하형 조명을 제외하면 모두 0.01 정도에 불과하여 우수한 색도균일성을 보여주었다. 본 연구에서는 또한 형광체 시뮬레이션의 신뢰성을 향상시키기 위해 측정된 발광스펙트럼에 기반해서 형광체의 흡수 및 여기 스펙트럼을 구하는 방법을 제시하였다.

Keywords

References

  1. E. F. Schubert and J. K. Kim, Science 308, 1275 (2005).
  2. E. F. Schubert, J. K. Kim, H. Luo and J.-Q. Xi1, Rep. Prog. Phys. 69, 3069 (2006). https://doi.org/10.1088/0034-4885/69/12/R01
  3. J. Y. Tsao, H. D. Saunders, J. R. Creighton, M. E. Coltrin and J. A. Simmons, J. Phys. D: Appl. Phys. 43, 354001 (2010). https://doi.org/10.1088/0022-3727/43/35/354001
  4. A. Mills, LEDs Magazine May/June, 36 (2007).
  5. J. S. Ryu, M.-Y. Yu, S.-M. Park, S. J. Kim and J.-H. Ko, New Physics: Sae Mulli 60, 56 (2010). https://doi.org/10.3938/NPSM.60.56
  6. C.-Y. Kim, S.-J. Kim, Y.-S. Choi, Y.-H. Han, S.-J. Yu, S.-G. Kim, Sae Mulli 50, 180 (2005).
  7. H. S. Cheong, C.-H. Hong and H. K. Cho, Sae Mulli 51, 79 (2005).
  8. E. S. Choi, Y. H. Choi and Y. J. Shin, Sae Mulli 59, 160 (2009).
  9. S. W. Park, H. D. Lee, T. H. Kim and J. H. Jeong, New Physics: Sae Mulli 61, 420 (2011). https://doi.org/10.3938/NPSM.61.420
  10. H. L Luo, J. K. Kim, E. F. Schubert, J. Cho, C.Sone and Y. Park, Appl. Phys. Lett. 86, 243505 (2005). https://doi.org/10.1063/1.1949282
  11. J. K. Kim, H. L Luo, E. F. Schubert, J. H. Cho, C.Sone and Y.Park, Jpn. J. Appl. Phys. 44, L649 (2005). https://doi.org/10.1143/JJAP.44.L649
  12. N. Narendran, Y. Gu, J. P. Freyssinier-Nova and Y. Zhu, phys. stat. sol. (a) 202, R60 (2005). https://doi.org/10.1002/pssa.200510015
  13. Y. Zhu and N. Narendran, J. Light & Vis. Env, 32, 115 (2008). https://doi.org/10.2150/jlve.32.115
  14. R. Kasegawa, Y. Ito, T. Tsukahara, Y. Oshima, A. Ono, N. Nada, T. Igarashi, T. Izawa and T. Kusunoki, IDW'09 Tech. Digest (Miyazaki, Japan, 2009), p. 1001.
  15. S. S. Jeong and J.-H. Ko, submitted to J. Inform. Display.
  16. B.-W. Lee and J.-H. Ko, IDW'11 Tech. Digest (Nagoya, Japan, 2011), p. 1365.