Daylight is an inherent attribute of a sustainable building. Artificial reproduction of natural illumination under varying needs and environmental conditions has been made possible after the appearance of the new wave of solid-state light sources. Our work is devoted to the development of white light-emitting diode (LED) clusters consisting of red, green, blue, and white (RGBW) LEDs for implementation in a smart lighting system that is able to reproduce light with correlated color temperature (CCT) similar to daylight, high values of color rendering index, and luminous efficacy. A method for determination of the optimal contribution of each of the four LEDs is demonstrated and discussed. We show that only three LEDs-green, blue, and white (no red) can be used in many cases for reproducing daylight. Both luminous efficacy of radiation and actual luminous efficacy of the considered RGBW clusters as functions of the CCT are analyzed.
The work is devoted to development of a smart lighting system that is able to change correlated colour temperature and consists of tunable 4-components RGBW clusters controlled via three channels. It is shown that fixing a ratio between the intensities of white and red LEDs at a level of 100:9 enables obtaining high values of colour rendering in a wide range of correlated colour temperatures. A control of 3 from 4 channels simplifies the system. The influence of the red LED on CRI and luminous efficiency is analysed. Full Text: PDF References:J. Gooley, S. Rajaratnam, G. Brainard, R. Kronauer, C. Czeisler and S. Lockley, "Spectral Responses of the Human Circadian System Depend on the Irradiance and Duration of Exposure to Light", Sci Transl Med 2, 31 (2010) [CrossRef]A. Borisuit, F. Linhart, J. Scartexxini, M. Munch, Light Res Technol 47, 192 (2014) [CrossRef]Q. Dai, W. Cai, L. Hao, W Shi and Z. Wang, Light Res Technol 50 (8), 1198-1211 (2017), [CrossRef]V. Kornaga, V. Sorokin, A. Rybalochka, O. Oliinyk and N. Kornaga, Semicond Phys Quantum Electron Optoelectron 18, 302 (2015) [CrossRef]Illuminating Engineering Society, ANSI/IES TM-30-18 IES method for evaluating light source color rendition (2018). New York, NY[DirectLink]Commission International de l'Éclairage, CIE 224:2017 Colour fidelity index for accurate scientific use (2017). Vienna [CrossRef]V. Kornaga, D. Kalustova and O. Oliynyk, Int Sci Conf "Light and power eng: hist, probl, perspect" 6, 43 (2018) [DirectLink]
In this paper, aspects of obtaining white colour hues for displays/monitors and lighting by using three-and four-components LED systems are discussed. Photometric equipment developed by us for multichannel LEDs control is used in an experimental study to verify theoretical calculations. Three-component RGB and four-component RGBW LED systems, which utilise the same RGB light sources and two white LEDs with warm and cold hues, are investigated. Results of testing of luminous efficacy of such systems at different values of light intensity and comparison of the corresponding circadian action factor as the value of impact of summarized RGB and RGBW white light on human circadian rhythms are presented. It is demonstrated that the four-component RGBW LED systems are more preferable for lighting and displays than the three-components RGB LED systems, because of significant higher luminous efficacy and slightly lower circadian factor over the entire range of correlated colour temperature from 2500K to 7000K studied.
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