Abstract

Taking color quality scale (CQS) as color rendering assessment criterion, the parameters including each color LED’s peak wavelength λi and fractional radiant flux Ii are optimized using genetic algorithm to maximize the luminous efficacy of radiation (LER) of the spectral power distributions (SPDs) of multi-color white light source with 3 to 7 components while maintaining the deviation of its color and color-rendering capability from that of the reference light source within the specified scope. Then the wavelength dependence of these SPDs is analyzed. It is shown that to achieve a Qa greater than 95 (5-color LEDs) or even close to 100 (7-color LEDs), the spectral energy could be concentrated in the range of 410~675 nm, indicating that this wavelength range makes a major contribution to high color rendering properties. Spectra filtering experiments show that spectrum around 580nm is harmful to color rendering. To obtain a white light source composed of 3-color LEDs with CQS Qa ≥ 80 and correlated color temperature (CCT) within 2700-6500K, the energy ratios among 410-495nm, 495-595nm, and 595-675nm intervals, can be simplified as that of the reference source with the same CCT.

© 2013 OSA

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References

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2010 (1)

W. Davis and Y. Ohno, “Color quality scale,” Opt. Eng.49(3), 033602 (2010).
[CrossRef]

1978 (1)

W. Walter, “Optimum lamp spectra,” J. Illuminating Engineering Society7(1), 66–73 (1978).

1972 (1)

H. H. Haft and W. A. Thornton, “High performance fluorescent lamps,” J. Illuminating Society2(1), 29 (1972).

1971 (1)

1967 (1)

H. D. Einhorn and F. D. Einhorn, “Inherent efficiency and colour rendering of white light source,” Illum. Eng.62(3), 154 (1967).

1943 (1)

1942 (1)

Davis, W.

W. Davis and Y. Ohno, “Color quality scale,” Opt. Eng.49(3), 033602 (2010).
[CrossRef]

Einhorn, F. D.

H. D. Einhorn and F. D. Einhorn, “Inherent efficiency and colour rendering of white light source,” Illum. Eng.62(3), 154 (1967).

Einhorn, H. D.

H. D. Einhorn and F. D. Einhorn, “Inherent efficiency and colour rendering of white light source,” Illum. Eng.62(3), 154 (1967).

Haft, H. H.

H. H. Haft and W. A. Thornton, “High performance fluorescent lamps,” J. Illuminating Society2(1), 29 (1972).

MacAdam, D. L.

Ohno, Y.

W. Davis and Y. Ohno, “Color quality scale,” Opt. Eng.49(3), 033602 (2010).
[CrossRef]

Thornton, W. A.

H. H. Haft and W. A. Thornton, “High performance fluorescent lamps,” J. Illuminating Society2(1), 29 (1972).

W. A. Thornton, “Luminosity and color-rendering capability of white light,” J. Opt. Soc. Am.61(9), 1155–1163 (1971).
[CrossRef] [PubMed]

Walter, W.

W. Walter, “Optimum lamp spectra,” J. Illuminating Engineering Society7(1), 66–73 (1978).

Illum. Eng. (1)

H. D. Einhorn and F. D. Einhorn, “Inherent efficiency and colour rendering of white light source,” Illum. Eng.62(3), 154 (1967).

J. Illuminating Engineering Society (1)

W. Walter, “Optimum lamp spectra,” J. Illuminating Engineering Society7(1), 66–73 (1978).

J. Illuminating Society (1)

H. H. Haft and W. A. Thornton, “High performance fluorescent lamps,” J. Illuminating Society2(1), 29 (1972).

J. Opt. Soc. Am. (3)

Opt. Eng. (1)

W. Davis and Y. Ohno, “Color quality scale,” Opt. Eng.49(3), 033602 (2010).
[CrossRef]

Other (11)

Y. Ohno and W. Davis, “Rationale of color quality scale,” (2010). http://www.digikey.com/us/en/techzone/lighting/resources/articles/rationale-of-color-quality-scale.html .

CIE, “Lighting of work places-Part 1: Indoor,” ISO 8995–1:2002(E)/CIE S 008/E:2001.

E. F. Schubert, Light-emitting diodes (Cambridge University Press, 2003).

CIE, “Method of measuring and specifying colour rendering properties of light sources,” in CIE 13.3–1995(CIE, Vienna, Austria, 1995).

CIE, “Colour rendering of white LED light sources,” in CIE 177:2007(CIE, 2007).

American National Standard, “Specifications for the Chromaticity of Solid state lighting Products (ANSI_NEMA_ANSLG C78.377–2008),” NEMA, 2008.

Lighting Research Center, Rensselaer Polytechnic Institute, “Developing Color Tolerance Criteria for White LEDs,” http://www.lrc.rpi.edu/programs/solidstate/assist/pdf/ColorDiscriminationStudy.pdf .

G. Wyszecki and W. S. Stiles, Color Science. Concepts and Methods, Quantitative Data and Formulae (Wiley, 2000).

J. Holland, Adaptation in Natural and Artificial Systems (The University of Michigan Press, 1975).

Z. Michalewicz, Genetic Algorithms + Data Structures = Evolution Programs, 3rd ed. (Springer-Verlag, 1996).

Matlab Documentation, “Global Optimization Toolbox,” http://www.mathworks.cn/help/toolbox/gads/bsc7xh9-2.html .

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Figures (6)

Fig. 1
Fig. 1

The flowchart of establishing the optimization model.

Fig. 2
Fig. 2

Optimized spectra of 3-, 4-, 5- and 7- colors white LED source with near maximum Qa for CCT of 3500K, 5000K, and 6500K.

Fig. 3
Fig. 3

The modification of optimized SPDs. Taking the original optimized SPD of 4 color-LEDs with Qa of about 60 and CCT of 3500K and that after modification as an example.

Fig. 4
Fig. 4

SPDs of 3-color LEDs white source optimized for the maximum luminous efficacy under CCT of 2700K~6500K and CQS Qa equal to or greater than 80.

Fig. 5
Fig. 5

Compare of SPDs of 3-color LEDs white source optimized for the maximum luminous efficacy under CCT of 2700K~6500K and CQS Qa equal to or greater than 80 with SPDs of respective reference source.

Fig. 6
Fig. 6

Energy ratio between B-, G- and R-interval of optimized SPDs of 3-color LEDs white source and that of the reference source with the same CCT.

Tables (3)

Tables Icon

Table 1 Change of Qa After Removing Spectrum Around 580nm for 3-color LEDs

Tables Icon

Table 2 Change of Qa After Removing Spectrum Around 580 nm for 4-color LEDs

Tables Icon

Table 3 Center Wavelengths of R-, G- and B-LED Under Different CCT

Equations (7)

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440nm λ i 680nm, i=1,2,,N
Δ i ={ 30nm, for 520nm λ i 550nm 20nm, for others , i=1,2,,N
0 I i 1, i=1,2,,N
I 1 + I 2 ++ I N =1
LER= 683lm/W× 380 780 S(λ) V(λ)dλ 380 780 S(λ) dλ
DS= g 11 d x 2 +2 g 12 dxdy+ g 22 d y 2 M 2
Q a (SPD) Q c

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