Vol.2 No.2 2009

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Interview : Energy-saving policy and standard research for solid-state lighting in the United States−168−Synthesiology - English edition Vol.2 No.2 (2009) market. This lamp makes things look brilliant. However, the assessment index of this light bulb is rather low. Yet, I think this is a very good light source to be used in actual practice. In industry, since R&D is conducted to raise the index value of manufacturing products, the development may head in the wrong direction if the index is wrong.(Ono)Here, you mean that the industrial standard itself that specifies the quality index is not good? (Ohno)Exactly. I thought there will be major problems if such poor LED products with a CRI of 80 are sold on the market.We’ve been doing this research for several years, and entered into the “Innovation Measurement Science,” which is a competition for a research budget hosted by the Director of NIST. Our proposal was selected for preliminary document screening, and I did a final presentation in front of the Laboratory Directors of NIST, and it passed. (Ono)Congratulations.(Ohno)First, we were doing simple experiments in a small inspection booth. We found that when objects were placed inside the booth and the RGB (red, green, and blue) spectra were slightly changed, the color rendering changed greatly. At a CRI of 82, which is a good value, the red sample appeared brown. This verified that my simulation was correct (Fig. 2). (Tanaka)Yes, I see. Comparing 82 and 71, 71 looks more vivid.(Ohno)71 appears very vivid, and your hand looks good when you put it in there. But in Energy Star, it has to be 75. If a CRI of 82 was selected for Energy Star, and not 71, there will be problems. The DOE told us “hurry up and make a new industrial standard.”(Ono)The values do not reflect the actual performance.Integrated progression of research and standardization (Ohno)This has been published as a paper, but we created a new index that will solve all such problems. We are proposing a new Color Quality Scale (CQS). In this index, the light with CRI=82 in Fig. 2 will have CQS=74, and the vivid light with CRI=71 will have CQS=83, and the numbers are reversed (Fig. 3). A new assessment method is meaningless unless it becomes an industrial standard, and people won’t use it unless it becomes an industrial standard. Color rendering is historically an international standard. Therefore, we made a proposal to the International Commission on Illumination (CIE) to set up a committee, where we presented our method, and we are continuing discussions.This research will come to fruition only after it becomes an international standard and is actually used by the industry. (Ono)Yes, indeed. We call this “an integrated progression of research and standardization.” Rather than starting to work on standardization after research is complete, we pick up the demand for standardization and this demand is reflected in the research. Then, the result is fed back to standardization. AIST claims that both must run together, and this is a good example. (Ohno)I certainly think so. Particularly, DOE’s Energy Star is already up and running, and the CRI is currently used because the new standard was not in time. Not just Energy Star, but also the entire SSL industry is advancing rapidly, (CRI>75)400700600500400700600500RGB-2 Emphasizing color contrastRGB-1 Optimized for CRI and energy efficiencyColor rendering of RGB LEDsCRI (Ra) = 82CRI (Ra) = 71Fig. 2 Color rendering of RGB LEDs.400700600500400700600500RGB-2 Emphasizing color contrastRGB-1 Optimized for CRI and energy efficiencyColor rendering of RGB LEDsCRI (Ra) = 82CRI (Ra) = 71CQS = 74CQS = 83Fig. 3 Color rendering of RGB LEDs.

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