Nguyen Doan Quoc Anh

Scattering effect of SiO2 particles on correlated color temperature uniformity of multi-chip white light LEDs

Abstract This study proposes the addition of SiO2 scattering particles into the phosphor layer of a multi-chip white light LED (MCW-LED) for enhancing its performance. It is demonstrated by computer simulations that SiO2 particles can bring significant effects on the correlated color temperature (CCT) uniformity and luminous flux. Through the simulation experiments, it was found that the MCW-LED with hybrid SiO2 structure with SiO2 particle size around 1 μm can achieve higher color uniformity than other package structures. We investigated the influence of SiO2 (quartz) concentration on the CCT and the output flux of the MCW-LED with CCTs 7000, 7700, and 8500 K, respectively. Compared to an LED package without SiO2, SiO2 packages can shrink the CCT deviation about 48%. In this study, it was demonstrated that the inclusion of about 5–10% SiO2 can produce an MCW-LED with higher CCT uniformity and optimal lumen output.

Improving the angular color uniformity and the lumen output for multi-chip white LED lamps by green Ce0.67Tb0.33MgAl11O19:Ce,Tb phosphor

Abstract In this paper, we propose and discuss how to enhance the color uniformity and the lumen output of multi-chip white LED lamps (MCW-LEDs). This can be done by combining the green Ce0.67Tb0.33MgAl11O19:Ce,Tb phosphor (CeTb) and phosphor compounding. We find that the proposed method can have a significant effect on MCW-LEDs performance. Through simulation results, it is confirmed that the color uniformity and the lumen output of MCW-LEDs with average correlated color temperatures of 7000 and 8500 K grow with the concentration of CeTb, while the color rendering ability decreases. With proper choice of CeTb concentration, good performance of MCW-LEDs can be obtained.

Y2O3:Eu3+ phosphor: a novel solution for an increase in color rendering index of multi-chip white LED packages

Abstract In this study, a novel compound is synthesized by adding the red-emitting Y2O3:Eu3+ dopant to conformal phosphor package (CPP) or in-cup phosphor package (IPP), to be employed as a component in multi-chip white LEDs lamps (W-LEDs). It was found that this solution can enhance the color rendering index (CRI) of W-LEDs that have correlated color temperatures of 5600 K through 8500 K to more than 86. Besides, the impacts of the Y2O3:Eu3+ phosphor on the attenuation of light through the phosphor layers, CPP and IPP, are also demonstrated based on the Beer–Lambert law and Mie theory. These results provide important information for producing W-LEDs with higher CRI.

Red-emitting α-SrO·3B2O3:Sm2+ phosphor: an innovative application for increasing color quality and luminous flux of remote phosphor white LEDs

Abstract By adding red-emitting α-SrO·3B2O3:Sm2+ phosphor and SiO2 co-doping particles to yellow-emitting YAG:Ce phosphor compound, a novel method for improving lighting performance of white LEDs with remote phosphor structure, which have an average correlated color temperature (CCT) of 5600–8500 K, is proposed and demonstrated. By varying α-SrO·3B2O3:Sm2+ concentration from 2 to 30% and maintaining 5% SiO2, the obtained results indicated that color rendering index (CRI), color quality scale (CQS), and luminous flux can be increased significantly. Moreover, the Mie-scattering theory is employed to verify the scattering properties, which have an effect on the enhancement of color quality and luminous flux. The results prove a prospective practical solution for manufacturing remote phosphor white LED (RP-WLED) having higher color quality and luminous flux.

Improvement of Optical Properties of White LED Lamps Using Green-Emitting Ce0.67Tb0.33MgAl11O19:Ce,Tb Phosphor

This study presents the improvement of performance of multi-chip white LED lamps (MCW-LEDs) having average CCTs of 7000 and 8500 K by using green-emitting Ce0.67 Tb0.33 MgAl11O19:Ce,Tb (CeTb) phosphor. The performance includes luminous efficacy and color uniformity which is analyzed based on Mie theory. Effects of CeTb concentration on optical properties of MCW-LEDs are also investigated. Optical simulations are employed by Light Tools software based on Monte Carlo method. Moreover, the scattering enhancement in CeTb case is demonstrated by Mie theory and Matlab soft-ware. The results show that both the luminous efficacy and color uniformity grow with CeTb concentration.

Design of a secondary lens using gaussian function

In the article, it is recognized that the high-intensity discharge (HID) fishing lamp becomes obsolete, so we designed a free secondary lens for an LED fishing/working lamp (LFWL) to serve the lighting needs of fishing and the on-board activities on fishing boats through gaussian decomposition for taking the place it. The results proved that it is really useful to the board, sea-surface, and underwater. Moreover, the lighting efficiency of 91 % with the power consumption reducing more than 3 times could be achieved when the proposed LED fishing/working lamps are used instead of the HID fishing lamps.In the article, it is recognized that the high-intensity discharge (HID) fishing lamp becomes obsolete, so we designed a free secondary lens for an LED fishing/working lamp (LFWL) to serve the lighting needs of fishing and the on-board activities on fishing boats through gaussian decomposition for taking the place it. The results proved that it is really useful to the board, sea-surface, and underwater. Moreover, the lighting efficiency of 91 % with the power consumption reducing more than 3 times could be achieved when the proposed LED fishing/working lamps are used instead of the HID fishing lamps.

Improving Color Uniformity and Color Rending Index of Remote-Phosphor Packaging White Leds by Co-Doping Sio2 And Sr2si5n8:Eu2+ Particles

Abstract Based on some advantageous properties, such as fast response time, environment friendliness, small size, long lifetime, and high efficiency, white LEDs are increasingly used in common illumination applications. In this research, by co-doping of redemitting Sr2Si5N8:Eu2+ phosphor and adding SiO2 particles to yellow-emitting YAG:Ce phosphor compounds, a new approach for improving color uniformity and color rending index of remote-phosphor structure white LEDs is proposed and demonstrated. The obtained results clearly indicate that the color rendering index (CRI) and color uniformity (ΔCCT) significantly depend on Sr2Si5N8:Eu2+ concentration. The results provide a potential practical solution for manufacturing remote-phosphor white LEDs (RP-WLEDs) in the near future.

Green-emitting (La, Ce, Tb)PO 4 :Ce:Tb phosphor: A novel solution for an increase in color homogeneity of white LEDs

We present the influence of green-emitting (La, Ce, Tb)PO4:Ce:Tb phosphor (LaTb) on the performance of the multi-chip white LED (MCW-LEDs) lamps including color homogeneity (CH) and color rendering index (CRI). By mixing the LaTb green phosphor and the YAG: Ce yellow phosphor compounding in a 7000 K MCW-LEDs, this new approach can produce a huge meaningful change in the CRI and the angular color distribution of MCW-LEDs. We also study the interaction between the concentration and size of the LaTb particles with CH, CRI. The obtained results demonstrate that higher CH could be attained by adding the LaTb particles.

A novel application of green (La, Ce, Tb)PO 4 :Ce:Tb phosphor on the luminous efficacy and color quality of white LEDs

In this paper, we propose a method to enhance luminous efficacy and color quality of the multi-chip white LED lamps (MCW-LEDs) at high color correlated temperature. This can be done by the incorporation (La, Ce, Tb)PO4:Ce:Tb green phosphor (LaTb) with YAG:Ce yellow phosphor compounding. Index, the employment this green phosphor into MCW-LEDs could bring a great effect on the optical performance of MCW-LEDs. Simulation results demonstrated that the optical properties at temperature of 8500K significantly improve with a size range from 1–10 μm and the LaTb concentration from 0–1.8%, while the color quality scale (CQS) slightly decreases. With the proper choice of LaTb particle size range around 6–8 μm and the concentration around 1.5%, the optimal lumen output and color quality of MCW-LEDs can be achieved.

Novel lighting properties of white LEDs with two-layered remote phosphor package using red-emitting α-SrO·3B2O3:Sm2+ phosphor

Abstract This paper investigates a method for improving the lighting performance of white light-emitting diodes (WLEDs), packaged using two separating remote phosphor layers, yellow-emitting YAG:Ce phosphor layer and red-emitting α-SrO·3B2O3:Sm2+ phosphor layer. The thicknesses of these two layers are 800 μm and 200 μm, respectively. Both of them have been examined at average correlated color temperatures (CCT) of 7700 K and 8500 K. For this two-layer model, the concentration of red phosphor has been varied from 2 % to 30 % in the upper layer, while in the lower layer the yellow phosphor concentration was kept at 15 %. It was found interesting that the lighting properties, such as color rendering index (CRI) and luminous flux, are enhanced significantly, while the color uniformity is maintained at a level relatively close to the level in one-layer configuration (measured at the same correlated color temperature). Besides, the transmitted and reflected light of each phosphor layer have been revised by combining Kubelka-Munk and Mie-Lorenz theories. Through the analysis, it is demonstrated that the packaging configuration of two-layered remote phosphor that contains red-emitting α-SrO·3B2O3:Sm2+ phosphor particles provides a practical solution to general WLEDs lighting.