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1
Content available remote Better color distribution uniformity and higher luminous intensity for LED by using a three-layered remote phosphor structure
Loan Nguyen Thi Phuong, Anh Nguyen Doan Quoc, Trang Nguyen Cong, Lee Hsiao-Yi
Materials Science Poland
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2022
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Vol. 40, No. 1
60--67
EN
Angular color distribution uniformity has been one of the most relevant properties in the development of white light-emitting diodes (WLEDs), since color consistency and uniformity are crucial factors in quality evaluation of a WLED. Here, particularly considering the need to overcome the poor chromaticity usually associated with WLED, we introduce a new design for the remote-phosphor package, namely a three-layered or triple-layer (TL) phosphor structure. Using three phosphor layers in packaging a WLED can result in higher color quality and luminous efficacy, compared to the double-layer (DL) configuration. In the present study, the results of using three remote phosphor layers indicate that although the structure using three layers has a lower color rendering index, the color quality scale is better than that available from the package with two layers. Additionally, the color-deviation values in the TL structure are smaller than in the dual-layer one, especially at high color temperatures (7,700 K and 8,500 K). Besides, in comparison with the DL model, the TL package increases the luminous flux by 1.4%–2%. Therefore, the TL remote phosphor structure possesses the greatest potential in enhancing the WLED quality.
2
Content available remote Triple-layer remote phosphor structure: a novel option for the enhancement of WLEDs’ color quality and luminous flux
Thi My Hanh Nguyen, That Phung Ton, Anh Nguyen Doan Quoc, Thanh Trang Tran
Materials Science Poland
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2020
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Vol. 38, No. 4
654--660
EN
The remote phosphor as a lighting structure has outstanding luminous efficiency compared to other options, such as conformal or in-cup. However, the lack of uniformity in distributed color has prevented remote phosphor from wider development. The answer to the chromatic performance enhancement that has been suggested by numerous researchers is the multi-layer configuration with two or three different types of chromatic phosphor. The research purpose is to select the best configuration for multi-chip white LEDs (WLEDs) to achieve optimal results in color quality scale (CQS), color rendering index (CRI), light output and color homogeneity. WLEDs mentioned in this paper have two distinct color temperatures, 6600 K and 7700 K. Experimental results show that the remote phosphor structure with three phosphor layers is superior in terms of color rendering, chromatic performance, and emitted light. The deviation of correlated color measured in this structure is also low, which means that the color uniformity is greatly enhanced in this multi-layer lighting structure. This result can be demonstrated by analyzing the scattering characteristics of the phosphoric layers using the Mie theory. The research findings have proven the effectiveness of the multi-phosphor configuration and can serve as a guideline to fabricate WLEDs with better performance.
3
Content available remote Eu2+-activated strontium-barium silicate: a positive solution for improving luminous efficacy and color uniformity of white light-emitting diodes
Thi My Hanh Nguyen, That Phung Ton, Anh Nguyen Doan Quoc
Materials Science Poland
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2020
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Vol. 38, No. 4
594--600
EN
In this research we have studied the lighting enhancement method by analyzing chromatic performance and luminous flux of light emitting diodes that produce white light. In order to achieve expected results, it is necessary to mix Eu2+-activated strontium-barium silicate (SrBaSiO4:Eu2+) with its phosphor compounding, which has been demonstrated to have considerable influence on lighting performance. The results showed that with the gradually increasing concentration of yellow-green-emitting SrBaSiO4:Eu2+phosphor in LEDs devices, at 8500 K, the color homogeneity and the lighting output received a great improvement. The color quality scale, on the other hand, responded negatively to the increase in SrBaSiO4:Eu2+. The impact of SrBaSiO4:Eu2+on optical properties of WLEDs was confirmed. The final step to optimize SrBaSiO4:Eu2+ usage in lighting development is to figure out a suitable amount of particles and optimize their size.
4
Content available remote Building superior lighting properties for WLEDs utilizing two-layered remote phosphor configurations
Anh Nguyen Doan Quoc, Ngoc Hoang Van
Materials Science Poland
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2020
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Vol. 38, No. 3
493--501
EN
The remote phosphor structure produces higher luminous flux but delivers poorer color quality than the conformal or in-cup phosphor structure. To eliminate this weakness, researchers have attempted to improve the chromatic properties of remote phosphor package. This study tends to enhance lighting features for WLEDs including color quality and luminous flux in general or color rendering index (CRI) and color quality scale (CQS) in particular by applying dual-layer remote phosphor structure. In the simulation section, we utilize two identical LEDs that only differ in correlated color temperature values which are 6600 K and 7700 K. The study offers an idea of placing a yellow-green phosphor layer SrBaSiO4:Eu2+ or a red phosphor layer SrwFxByOz:Eu2+,Sm2+ on the yellow phosphor layer YAG:Ce3+ and then modifying the concentrations of SrwFxByOz:Eu2+,Sm2+ and SrBaSiO4:Eu2+ to the suitable values to improve the color quality and lumen output of WLEDs. The results show that red phosphor layer SrwFxByOz:Eu2+,Sm2+ has a significant influence on CRI and CQS improvement. Particularly, the increase of SrwFxByOz:Eu2+,Sm2+ concentration leads to increased CRI and CQS because the red light component increases in WLEDs. On the other hand, the green phosphor layer SrBaSiO4:Eu2+ only brings benefit to the luminous flux. However, the WLEDs’ luminous flux and color quality drop sharply, when SrwFxByOz:Eu2+,Sm2+ and SrBaSiO4:Eu2+ concentrations rise extremely, which is verified based on the Mie-scattering theory and the Lambert-Beer law. In short, the article provides general knowledge and primary information for the production of higher-quality WLEDs.
5
Content available remote Analiza wpływu temperatury na pracę różnych rodzajów źródeł światła z zakresu profesjonalnej techniki świetlnej
Łączny P., Seredyński P., Chmielowiec K., Butryn W.
Przegląd Elektrotechniczny
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2017
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R. 93, nr 6
119--124
PL
Celem niniejszego artykułu jest przedstawienie wpływu zmian temperatury otoczenia na pracę różnych typów źródeł światła z zakresu profesjonalnej techniki świetlnej. W ramach przeprowadzonych badań dokonano analizy zmian całkowitego strumienia świetlnego, mocy czynnej oraz skuteczności świetlnej dla źródła żarowego, lamp LED, fluorescencyjnych, sodowych oraz lampy metalohalogenkowej. Zebrane wyniki pozwoliły na określenie jaki zakres temperatur jest optymalny dla maksymalnej wydajności oraz sprawności energetycznej rozważanych źródeł światła.
EN
The purpose of this article is to present the impact of changes in ambient temperature on the operation of different types of light sources in the field of professional lighting technology. In the framework of the study the following indicators were tested: the total lumen output, active power and the efficiency of incandescent lighting source, LED lamps, fluorescent, sodium and metal halide lamps. The collected results allowed to determine which temperature range is optimal for maximum productivity and energy efficiency of the considered light sources.
6
Content available Investigation of contemporary illuminants characteristics. The led lamps example
Goshko M.
ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes
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2016
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Vol. 5, No 3
205--209
EN
The problems of investigation of contemporary illuminants characteristics are considered. Particularly the LED lamps of the following trade marks were tested: «Maxus», «Electrum», «Lemaso». Photometric and electrotechnical parameters, stated by the producers, were tested. The investigation revealed that the stated illuminants’ power did not correspond to the actual experimental data, in some cases the 8% exceeding was registered (Lemaso). On the other hand, the actual power of “Maxus” and “Electrum” LED lamps was lower than stated, -22,5 % and -2,35 % accordingly. The low power coefficient is the major drawback of LED lamps in Ukrainian market. Its actual value ranges are 0,4–0,65, whereas its minimal value for a LED lamp of 5-25 Watt power is considered to be not less than 0,8.
7
Content available Investigation of contemporary illuminants characteristics the led lamps example
Goshko M.
ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes
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2015
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Vol. 4, No 4
65--70
EN
The problems of investigation of contemporary illuminants characteristics are considered. Particularly the LED lamps of the following trade marks were tested: «Maxus», «Electrum», «Lemaso». Photometric and electrotechnical parameters, stated by the producers, were tested. The investigation revealed that the stated illuminants’ power did not correspond to the actual experimental data, in some cases the 8% exceeding was registered (Lemaso). On the other hand, the actual power of “Maxus” and “Electrum” LED lamps was lower than stated, -22,5 % and -2,35 % accordingly. The low power coefficient is the major drawback of LED lamps in Ukrainian market. Its actual value ranges are 0,4–0,65, whereas its minimal value for a LED lamp of 5-25 Watt power is considered to be not less than 0,8.
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