In this paper, we perform experiments by varying temperature and electrical current, and carry out the theoretical spectral optimization primarily on one-phosphor-coated three-hump white light-emitting diode (LED) for healthy indoor or outdoor lighting by using the genetic algorithm (GA). We obtain low circadian action factor (CAF) or high CAF according to different application occasions (such as bedroom lighting or office lighting), good CIE (Commission Internationale de L-Eclairage) color rendering index (CRI, Ra) or IES (Illumination Engineering Society of North America) color fidelity index (CFI, Rf) and color gamut index (CGI, Rg) or other color performances, and possibly high luminous efficacy of radiation (LER, K) at various correlated color temperatures (CCTs) from 2700 K to 6500 K. For instance, in the case of one-phosphor-coated three-hump white LEDs at CCT=3000 K, the low CAF as 0.264 (Ra =80, Rf =77, Rg=103, K=350.0 lm/W) can be achieved, while that of standard light at the same CCT is 0.407. In addition, we also compare four types of three-hump white LEDs in performances of circadian action, luminous efficacy of radiation, and color rendering. This work can help both industry and academia understand the application of three-hump white LEDs in the healthy indoor or outdoor lighting.

The concept of human-centric lighting is gradually emerging. People no longer only consider the lighting function of light, but also begin to pay attention to the comfort and health of light. In this article, we perform an investigation on the circadian regulation of four-primary light-emitting diode (LED) based displays for the people with various ages from 1 year old to 100 years old. The double-Gaussian function is used to mimic the spectral power distribution of monochromatic LED. The main figures of merit of LED display performance are color gamut of Rec. 2020, luminous efficacy of radiation, correlated color temperature (CCT), and also non-visual parameters, such as circadian stimulus and melanopic efficacy of luminous radiation provided by Commission Internationale de l'Eclairage (CIE) standard. Then, the genetic algorithm is adopted for performing the spectral optimization of four-primary LED display while many constraint conditions are set, such as CCT values (2700 K and 6500 K), CCT tolerance, and color distance ( D _uv < 0.01) in the CIE 1960 UCS color space. Related results of visual and non-visual characteristics are also compared with those of three-primary LED displays. This work would pave a way for the development of healthy four-primary LED display in consideration of various ages of people.