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Augmenting color homogeneity and luminous flux of WLEDs with dual-layer structure of the remote phosphor package

H. Y. LIAO1, N. T. P. LOAN2, L. V. THO3, P. T. THAT4, P. X. LE5, N. D. Q. ANH6, M. J. CHEN1, J. C. CHANG1, H. Y. LEE1,*

Affiliation

  1. Department of Electrical Engineering, National Kaohsiung University of Sciences and Technology, Kaohsiung, Taiwan
  2. Faculty of Fundamental 2, Posts and Telecommunications Institute of Technology, Ho Chi Minh City, Vietnam
  3. Institute of Tropical Biology, Vietnam Academy of Science and Technology, Ho Chi Minh City, Vietnam
  4. Faculty of Electronics Technology, Industrial University of Ho Chi Minh City, Ho Chi Minh city, Vietnam
  5. Faculty of Electrical and Electronics Engineering, HCMC University of Food Industry, Ho Chi Minh city, Vietnam
  6. Faculty of Electrical and Electronics Engineering, Ton Duc Thang University, Ho Chi Minh City, Vietnam

Abstract

This article indicates the impacts of the distance between two phosphor layers (d1) and the distance between the phosphor layer with the LED surface (d2) on the optical properties of the remote phosphor structure. When the distances d1 and d2 are varied, the scattering and absorption properties of the remote phosphor layer change dramatically, which causes a huge influence on the color uniformity and illumination capability of WLEDs. To keep the correlated color temperature of WLEDs stable at 8500 K in case d1 and d2 are adjusted, the concentration of YAG:Ce3+ phosphor also needs to be modified. When d1 = d2 = 0, the scattering and absorption in the remote phosphor layer is minimum, leading to the infinitesimal color and luminous flux. This can be attested by the effects of the spectra generated in case these distances fluctuate. The larger the d1 and d2 get, the larger the scattering surface is, and the more homogeneous the blending of the blue and yellow rays becomes, which leads to the minimum white light deviation and simultaneously leads to the lowest luminous flux. According to the studied results, the luminous flux can be maximum at 1020 lm when d1 = 0.08 mm or d2 = 0.63 mm. Meanwhile, the smallest color deviation that is the paramount color consistency occurs when d1 = 0.64 mm or d2 = 1.35 mm. Consequently, choosing the two distances d1 and d2 becomes tremendously vital for the manufacturers who have to depend on the production objective to get well-chosen option. The research results will provide further information for this decision in order to better the quality of WLEDs.

Keywords

WLEDs, Dual-layer structure, Remote phosphor package, Color homogeneity, Luminous flux.

Citation

H. Y. LIAO, N. T. P. LOAN, L. V. THO, P. T. THAT, P. X. LE, N. D. Q. ANH, M. J. CHEN, J. C. CHANG, H. Y. LEE, Augmenting color homogeneity and luminous flux of WLEDs with dual-layer structure of the remote phosphor package, Optoelectronics and Advanced Materials - Rapid Communications, 14, 5-6, May-June 2020, pp.214-219 (2020).

Submitted at: July 29, 2018

Accepted at: June 16, 2020