A tunable white LED package is a multi-emitter device that integrates a minimum of two channels of individually controllable LEDs. Typically, the semiconductor package is a 2-in-1 assembly that combines warm white LEDs and cool white LEDs to enable tuning of the correlated color temperature (CCT) between chromaticity points of each primary color. There also may be 3-in-1 devices that additionally incorporates a neutral white LED primary such that the chromaticity coordinates can be set more precisely along the black body locus (the Planckian locus). Adjusting the amount of current delivered to each of the LED primaries will change the color mixing ratio and tune the overall CCT of an LED package. The CCT range of a tunable white LED package is defined the CCTs of LEDs at each end of the CCT range. In typical tunable white lighting applications, the warm white LEDs have a CCT usually around 2700 K and the cool white LEDs have a CCT usually around 6000 K.
Tunable white lighting is the enabling technology of human centric lighting (HCL). HCL is the science of creating environmental cues for synchronizing human circadian rhythms to the light/dark cycles of the 24-hour day. It brings the dynamics of natural daylight into our living and working spaces, evoking particular human biological responses to support health, wellbeing, and performance. Light is a fundamental part of our life. Both the visual system and the biological system have evolved under a natural regime of daylight and darkness. The retina has developed photoreceptors that detect optical radiation for vision, physiological and psychological responses. Optical radiation reaching the retina not only enables humans to understand the physical universe, it also stimulates non-visual effects on human psychology and physiology. As humans spend the vast majority of their time working and living indoors, the impacts of artificial lighting on a range of neuroendocrine and neurobehavioral responses are hard to ignore.
at the Open Lighting Product Directory (OLPD)
