Technology develops because of human needs, and it raises new needs of human. Because of our desire for brightness and fear of darkness, artificial lights came along. Due to limitation of technologies, the original pursuit of artificial lights was illumination. Nowadays, however, as lighting technologies (especially LED lighting technologies) bloom, artificial lights are not just about illumination anymore, they are more about atmosphere, experience, and lifestyle.
Compared to conventional technologies, LED lighting excels in energy efficiency, color customizability, and space for optical design. It can easily create any types of atmosphere, whether it is bright and colorful, or warm and cozy. The magic of LED lighting makes it a landmark in human lighting history.
In recent years, healthy lighting has gradually replaced the role of efficient lighting and become the new trend of the industry. High color rendering performance and sunlight simulation are the new criteria for lighting fixtures. Particularly, in working or living places where people stay for long, light is supposed to be tunable according to people’s needs. It can even mimic sunlight, which changes color with time. It makes it possible for those who stay in door all day to experience the life of “rise at dawn, rest at dusk”.
Currently, the most common way of making tunable-white LED lights is mixing two color temperatures in one lighting fixture. It makes the light tunable by mixing the spectra of a low CCT white LED (warm white) and a high CCT white LED (cold white). In Figure 1, the red crosses indicate the color coordinates in the tunable range of a light mixing 2700K and 6500K sources. It is distinct that in the center area, the coordinates deviate from the black body curve, and the CRI values drop greatly.
Figure 1. Color rendering performance of lights mixing two color temperatures
Apart from the mixing solution, there is another way that combines three types (R, G and B) of chips and one white LED source to make a tunable-white LED light. This method expands the tunable range, but because the chips have narrow spectral width, CRI values at some color temperatures are relatively low. What’s more, the three chips have different voltages and decay trends, which makes further circuit design complicated, and the working reliability unguaranteed.
To solve the issues above, YUJI spent two years on research and development. With its expertise in LED phosphor and packaging technologies, Yuji successfully developed the Spectrum-X series, a solution combining the same excitation LED chips and multiple phosphors. This tunable-white LED light source has theoretical CRI over 95 at all color temperatures, perfectly unravelling the issues raised by the previous two solutions in terms of tunable range and color rendering ability. In our performance tests, the Spectrum-X showed an overall outstanding color rendering ability from 2700 K to 10000 K. The result can be seen from Figure 2 that the chromaticity coordinates are almost all on the black body curve.
Figure 2. Color rendering performance of Spectrum-X in its tunable range
Besides, Spectrum-X adopts the same blue chips or same purple chips, which both have the controllable voltage range within ±0.05 V. Together with the unique YUJI phosphor, it ensures that every single color of Spectrum-X has high reliability and consistent decay tendency. This makes the circuit design much easier, and the product quality more controllable.
Due to the special properties of Spectrum-X, it only accepts custom orders for now. For further information about Spectrum-X series products, please contact firstname.lastname@example.org or stay tuned for further updates on YUJI’s official website www.yujiintl.com or our online store store.yujiintl.com.