(Author: Judy Lin, Chief Editor, LEDinside)

Product development in the LED industry has changed significantly over the past years, shifting from boosting lumen efficiency to prioritizing light quality. Lumileds latest LUXEON Stylist Series, designed to meet different commercial and retail lighting demands, especially emphasizes CoB LED color performance. Compared to the company’s older generation products, the new LEDs are incorporating TM-30 color parameter measurements into the design process.

Challenges of finding the right color balance

The most difficult part of designing color enhancing LEDs lies in finding the right phosphor formula to fine tune the color performance. However, finding the different formula, recipe, and proportion is a very complicated process. To solve this issue, Lumileds designs and manufactures its own phosphors.

 “Lumileds has a clear advantage as it has a dedicated in-house facility in Germany to engineer customized phosphors for specific applications,” said Luis Acena, Senior Manager of LUXEON Stylist Series. “This facility basically experiments with different phosphors, and build different recipes of phosphors to achieve the right spectra and color pointsthat retailers and lighting designers love.”

Moreover, LED manufacturers want to increase the color saturation without making it appear unnatural. CrispColor Technology™ LEDs delivers more saturated and vivid colors with a wider gamut area than high CRI white LEDs. The challenge for LED manufacturers is to deliver highly saturated colors and a pure white at the same time. To solve that issue, CrispColor Technology from the LUXEON Stylist Series controls with precision the white color point, situated strategically in a specific area below the Black Body line.

For the whitest whites in retail applications, Lumileds offers its CrispWhite Technology  with an engineered spectra that provides a double peak made of blue and violet LEDs to activate the Fluorescent Whiting Agents (FWA) in fabrics to make whites appear whiter.

Replacing CRI measurements with TM-30

A long debated color metric question in the LED industry is whether the conventional Color Rendering Index (CRI) established in 1974 should be overhauled, as the outdated index based on conventional light sources only measures hue consistency. The 90 color samples are unsaturated, while the new TM-30 adds a new parameter, Gamut Area Index (GAI), that measures hue saturation. The way the colorimetry was measured with CRI, by averaging the lights’ performance for 90 color samples, also made it easier for manufacturers to game the system and difficult for customers to foresee the real color performance in the application.

Introduction of the TM-30 in the industry has been met with resistance, similar to that observed in the earlier years of introducing Color Quality Scale (CQS), noted Acena. Even though the two color performance indicators are more accurate and comprehensive in colorimetry measurements than CRI, the biggest issue is it requires manufacturers to update existing measurement systems, redesign product specs, update all printed information and reeducate their employees and customers. Time consuming and costly changes that have been met with reluctance in the industry.

The new LUXEON CoB with CrispColor Technology is based on Yoshi Ohno of the National Institute of Standards and Technology’s (NIST) colorimetry of light sources studies published in 2015. Ohno’s study is based on an earlier research by The Lighting Research Center at Rensselaer Polytechnic Institute, where the research center tried to determine how people from different races, genders, and ages perceived white and other light colors. LRC results showed most people preferred warm white colors of 2200K to 4000K below the Black Body Line (or Planckian Locus­), and colors exceeding 4000K above the line.

Ohno’s study enlarged the size of test subjects and extended the chromatic adaptation period of light exposure to human eyes. The result of his findings were slightly different from LRC, where the range of preferred white color reportedly was broader, ranging from 2200K to 6500K. The adjustment was made to remove the effects of gamut and chroma saturation and fully adapt the subject to the illumination..

Lumileds LUXEON Stylist Series Designed to Meet Different Retail Lighting Color Requirements

The LUXEON Stylist Series can be split into three major applications including fashion retail, fresh food, and restaurants. For fashion retail applications the LEDs include LUXEON CoBs with CrispColor Technology and second generation CrispWhite Technology LEDs. LEDs with CrispWhite Technology that highlights whites are designed to replace metal halogen lights, and cover a color temperature of 3,000K with alumen output ranging from 653 lumens in the 1202 CoB to 6,766 lumens in the 1216 CoB. LEDs with CrispColor Technology are mostly designed with replacing halogen lighting in mind but also high CRI metal halide. The launch date for the retail application LEDs is scheduled to take place on July 12, 2016 this year.

Lighting for restaurant applications which features 2200K ultra-warm LEDs to create a comfortable ambient lighting atmosphere is also scheduled to reach the market later this month, according to Lumileds.

The company’s FreshFocus Technology^TM to enrich food colors with lights include those focused on bringing out the warm yellow colors in bread and pastries, such as LUXEON CoBs extra warm light with 2,700K color temperature.

Different types of meats also have specially designed lighting to enhance reds and natural whites in meats. In the LUXEON Stylist Series, FreshFocus Technology for red meat is able to achieve closer to 2200K color temperature with a special spectra to enhance the red rendering, while FreshFocus Technology for marbled meat or white meat has a color range between 3500K to 4000K with a tuned spectra to balance a good red rendering with natural whites. As for lighting to enhance fish meat, this is in the cool white range of 6500K with very high CRI. The launch date for the FreshFocus Technology LEDs for fresh food will take place in around the third quarter of 2016.

To conclude, as market competition in the general lighting sector intensifies, more manufacturers are shifting towards developing lighting products that prioritize light quality rather than raising light efficiency. The move towards better lighting quality also is calling to attention better color performance in lighting, hence highlighting the importance of phosphor technology and related recipes. Companies that are able to specifically match recipes to desired application sectors, such as Lumileds, will have greater leverage in niche and high end lighting market applications that will result in higher profits.