Red, green, blue, and white clusters for daylight reproduction

Abstract

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.

Color temperature tunable RGBW cluster with optimize color rendering and efficacy

“…Since the luminous efficacy decreases with increasing the RGB contribution, the leftmost points correspond to the maximum RGB contribution, whereas the rightmost ones correspond to the minimum RGB contribution, i.e., when the point RGB lays on the triangle side or, in other words, when only two color LEDs are used. 14 Both CIE CRI and IES Rf curves have in general similar behavior. The maxima of CRI and Rf (Rf max ) coincide with the maxima of the corresponding luminous efficacies only for a few CCT.…”

“…Recently, it has been reported about the study on RGBW SLSs when the contribution of the RGB LED to the white light generation is minimal. 14 In this case, the RGB point lies on a side of the RGB triangle. The corresponding approach enables one to use a three-channel control circuit because only three of the four LEDs work.…”

White Colour Hues in Displays and Lighting Systems Based on RGB and RGBW LEDs

“…Therefore, the imposition of an additional condition is required. We have chosen the condition of minimization the contribution of colour RGB LEDs [13], assuming that reducing the contribution of less efficient LEDs should increase the luminous efficacy of the resulting light. Thus, the resulting chromaticity coordinates can be unambiguously determined as follows:…”

“…But adding a white LED to RGB LED lighting systems greatly expands its capabilities. In RGBW LED lighting systems it is possible to implement a number of algorithms for optimizing white parameters both in terms of luminous efficacy and in terms of significantly increasing the values of the CRI to values greater than 90 in a wide range of CCT [2,[13][14][15].…”

Led Group Control System for Research of Color Mixing Methods

“…Системи освітлення з можливістю налаштування світлових і колірних характеристик як багатопараметричні об'єкти конструювання вимагають розроблення нових методів змішування кольорів [5], самодіагностування, передавання інформації між окремими системами та основним вузлом керування, формування адаптивних кривих сили світла [6,7], а також ефективного змішування світла від світлодіодів різних типів. У системі повинно бути реалізовано декілька каналів керування різними типами світлодіодів [8,9], і, оскільки вони мають певну залежність своїх фотометричних характеристик від температурного режиму роботи та струму керування, система повинна забезпечувати високу їх стабільність чи певним чином враховувати.…”