Abstract

The correlated color temperature (CCT) tunable white-light LED cluster, which consists of direct-emission blue and red LEDs as well as phosphor-conversion (PC) LEDs packaged by combining green and orange phosphors with a blue LED die, has been obtained by nonlinear program for maximizing luminous efficacy (LE) of radiation (LER) under conditions of both color rendering index (CRI) and special CRI of R9 for strong red above 90 at CCTs of 2700 K to 6500 K. The optimal peak wavelengths of blue LED, red LED, blue LED die, green and orange phosphors are 465 nm, 628 nm, 452 nm, 530 nm and 586 nm, respectively. The real CCT tunable PC/red/blue LED cluster with CRIs of 90~96, R9s of 90~96, CQSs of 89~94, LERs of 303~358 lm/W, and LEs of 105~119 lm/W has been realized at CCTs of 2722 K to 6464 K. The deviation of the peak wavelength should be less than ± 5 nm for blue LED die, ± 1 nm for red LED, and ± 2 nm for blue LED to achieve the PC/R/B LED cluster with high optical performance.

©2012 Optical Society of America

1. Introduction

It has been reported that a new class of light-detecting retinal cells, the ganglion cells, send their signals to the brain's circadian clock [1, 2]. Inappropriate lighting conditions were shown in mammals to upset the body chemistry and to lead to deleterious health effects, including cancer [3]. Thus, circadian light sources with tunable color temperature would be beneficial to human health, well-being, and productivity. Furthermore, such circadian lights could lead to a reduced dependence on sleep-inducing pharmaceuticals. For this reason, sources replicating the Sun’s high color temperature during the midday period and low color temperatures during early morning and at night would be a wonderful illumination source, given that we humans adapted to such a circadian source during evolution. Alternatively, we may want to influence and manipulate the human circadian rhythm: If circadian lights could reduce driver fatigue, the number of traffic accidents and fatalities caused by this condition could be reduced as well [4]. The challenge in the design of white light LED clusters with correlated color temperature (CCT) tunable consists of achieving excellent color rendering index (CRI) values [5] over a reasonable range of color temperatures, while at the same time maximizing their luminous efficacies (LEs). Some CCT tunable white-light LED clusters have been discussed [610]. It was found that the NW/R/B cluster consisting of blue (463.0 nm) and red (631.9 nm) LEDs as well as the NW LED with the CIE 1931 chromaticity coordinates of (0.3718, 0.4485) is the simplest solution for high CRI as well as high LE. It is noticed that the chromaticity point of NW LED is well above the Planckian locus in the yellow-green region and the NW LED does not comply with the ANSI standard for white LED (ANSI C78.377). Thus the NW/R/B cluster provides a triangular color gamut that encompasses the Planckian locus, and it is possible to achieve CCT tunability. The NW/R/B cluster with CRI above 85 has been demonstrated, but the special CRI of R9 for the strong red was below 70 [8]. One problem with the CRI is that it can give fairly high scores to sources that render some saturated object colors very poorly [11, 12]. In particular, the report from CIE Technical Committee TC 1-62 “Color rendering of white LED light sources” [13] summarizes several problems of the CRI when applied to white LED sources. The CRI score does not correlate well with visual evaluation in many cases. One of reasons was assumed to be the different order of magnitude of the color differences occurring if the reflecting samples are illuminated by a white LED light source and by other light sources, due to the peculiar spectral power distributions of the white LED light sources “interacting” with the spectral reflectance of the test-color samples. This is especially noticeable for the case of test-color sample No. 9 of the CIE method which is a strong red test-color sample. An improved indicator, color quality scale (CQS), has recently been proposed by National Institute of Standards and Technology [14]. It was found that the CQS provides scores consistent with the CRI for the most recent phosphor type LED products, RGBA LEDs and traditional discharge lamps [14]. So the CRI as a metric for evaluating the color rendering abilities of white-light sources is suitable for the white LED cluster with the phosphor-conversion LED (PC LED). Some spectral optimizations for CCT untunable white-light LEDs have been discussed [1522]. However, the spectral optimization for CCT tunable white-light LED cluster has not been explored till date. In this work, the CCT tunable PC/R/B LED cluster with high luminous efficacy of radiation (LER) and excellent CRI, which consists of direct-emission blue and red LEDs as well as PC LEDs packaged by combining green and orange phosphors with a blue LED die, has been obtained by nonlinear program for maximizing LER while both CRI and R9 above 90 at CCTs of 2700 K to 6500 K with chromaticity difference from the Planckian or daylight locus on the CIE 1960 uv chromaticity diagram (dC) below 0.0054. The special CRI of R9 for strong red is considered because the red-green contrast is very important for color rendering, and red tends to be problematic. Lack of red component shrinks the reproducible color gamut and makes the illuminated scene look dull [23, 24]. The real CCT tunable PC/R/B LED cluster with high luminous efficacy and excellent color rendering property is fabricated in our laboratory. The effect of the deviations from peak wavelengths of the blue LED die, red LED and blue LED of the real PC/R/B LED cluster is presented.

2. Spectral optimization of the CCT tunable PC/R/B LED cluster

The CCT tunable PC/R/B LED cluster consists of the PC LED with a blue LED die, green and orange phosphors, direct-emission red and blue LEDs. The relative spectral power distribution (SPD) of the PC/R/B LED cluster, SPC/R/B (λ), is given by,

SPC/R/B(λ)=kPCSPC(λ,λb,λg,λor)+kRSR(λ,λR)+kBS(λ,λB)
where SPC(λ, λb, λg, λor), SR(λ, λR) and SB(λ, λB) refer to the spectra of PC LED, red and blue LEDs, λb, λg, λor, λR and λB refer to peak wavelengths of blue LED die, green phosphor, orange phosphor, red and blue LEDs, kPC, kR and kB are proportions of relative SPDs of the PC LED, red and blue LEDs, respectively. The relative SPD of the PC LED, SPC(λ, λb, λg, λor), is given by,
SPC(λ,λb,λg,λor)=qbSb(λ,λb)+qgSg(λ,λg)+qorSor(λ,λor)
where Sb(λ, λb) refers to relative SPD of the blue spectrum transmitted through the phosphors, Sg(λ, λg) and Sy(λ, λy) refer to the relative emission spectra of green and orange phosphors, qb, qg, and qor are proportions of the relative emission spectra of green and orange phosphors, respectively.

Consider a SPD that contains emission spectrum from InGaN blue and AlGaInP red LEDs as well as PC LEDs with an InGaN blue LED die, silicate green and orange phosphors of the PC/R/B LED cluster. We employ He-Zheng model [7] of SPDs for AlGaInP red LED, InGaN blue LED and silicate phosphors. Since photon energy linewidths of InGaN blue and AlGaInP red LEDs about 5 kT and 2 kT respectively, half-spectral-width (HSW) [7] of SB(λ, λB) and SR(λ, λR) are assumed to be 28 nm and 20 nm, respectively, and HSWs of Sb(λ, λb) is assumed to be 32 nm duo to broadening blue spectra transmitted through the phosphors. In spectral optimization, we assume that the peak wavelength and the half-spectral-width of LED are independent on the drive current. So, the SPC/R/B (λ) will obey the linear combination of the SPC(λ, λb, λg, λor), SR(λ, λR), and SB(λ, λB) with the proportional factors kPC, kR, and kB, respectively. As well as the SPC (λ, λb, λg, λor) will obey the linear combination of the Sb (λ, λb), Sg(λ, λg), and Sor (λ, λor) with the proportional factors qb, qg, and qor, respectively. In realization of the PC/R/B LED cluster, we need to consider the nonlinearity with drive current.

Subjecting the 11-dimensional parameter space to three color-mixing constrains results in the location of the feasible vectors on the hypersurface with 8 dimensionality [25]. In order to optimize spectra of the CCT tunable PC/R/B LED cluster, we introduce an objective function:

F(λb,λg,λor,λR,λB,qb,qg,qor)=i=18LERi(i=1,2,3,8)(underconditionsofCRIi90andR9i90withdC0.0054)
where the subscripts i = 1, 2, 3, 4, 5, 6, 7 and 8 refer to 2700 K, 3000 K, 3500 K, 4000 K, 4500 K, 5000 K, 5700 K and 6500 K of CCTs of the PC/R/B LED cluster, respectively. Hence, the optimization problem reduces to finding maxima of the objective function under conditions of CRI ≥ 90 and R9≥ 90. In this work, a fast Pareto genetic algorithm [26] was chosen because they are able to scan a vast set of solutions, they do not depend on a starting solution, they are very useful for complex problems, and most importantly, they can be easily modified to estimate the Pareto optimal set. Nine silicate green (512 nm~554 nm) phosphors and five silicate orange (580 nm~606 nm) phosphors (Intematix Corporation) are used in optimization [19]. The CCT tunable PC/R/B LED cluster with ultrahigh CRI and R9, as well as high LER at CCTs of 2700 K to 6500 K has been obtained by nonlinear program for maximizing the objective function F while both CRI and R9 above 90. Optimized peak wavelengths of blue LED, red LED, blue LED die, silicate green and orange phosphors are 465 nm, 628 nm, 452 nm, 530 nm and 586 nm, respectively. The optimal proportions of the relative emission spectra of the blue LED die, green and orange phosphors in the PC LED are 0.3828, 0.9272 and 0.5864, respectively. The relative radiation fluxes of blue LED die, the green and orange phosphors in the PC LED are 9.48%, 56.00%and 34.52%, respectively. The relative radiation fluxes of the green and orange phosphors in the PC LED are 61.86% and 38.14%, respectively. The CIE 1931 chromaticity coordinates of the PC LED are around (0.3717, 0.4803). The optimal relative SPDs of PC, red (628 nm) and blue (465 nm) LEDs are shown in Fig. 1 . The PC/R/B LED cluster provides a triangular color gamut that encompasses the Planckian locus from 2222 K to 100000 K (shown in Fig. 2 .), so it is possible to achieve CCT tunability. The optimal results of the CCT tunable PC/R/B LED cluster are shown in Table 1 .

 figure: Fig. 1

Fig. 1 Optimal and real relative SPDs of PC, red and blue LEDs

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 figure: Fig. 2

Fig. 2 The PC/R/B LED cluster provides a triangular color gamut that encompasses the Planckian locus from 2222 K to 100000 K, so it is possible to achieve CCT tunability. Also showing the chromaticities of real PC/R/B LED cluster at CCTs of 2722 K, 3040 K, 3514 K, 4024 K, 4574 K, 4968 K, 5719 K and 6464 K.

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Tables Icon

Table 1. CRI, R9, CQS and LER of the optimal PC/R/B LED cluster at CCTs of 2700 K to 6500 K.

The simulation results show that the PC/R/B LED cluster could realize CCT tunable white-lights with CRIs of 90~96, R9s of 91~96, CQSs of 90~95 and LERs of 301~357 lm/W at CCTs of 2700 K to 6500 K. The PC LED with the SPD as shown in Fig. 1 could be realize high LE, and the relative luminous flux of the PC LED in the PC/R/B LED cluster exceeds 77% at CCTs of 2700 K to 6500 K. Therefore, the PC/R/B LED cluster could realize CCT tunable white-light with excellent color rendering property as well as high luminous efficacy.

3. Realization of the CCT tunable PC/R/B LED cluster

The PC LED (x = 0.3715, y = 0.4851 and LE = 127.6 lm/W at IF = 350 mA) with the InGaN blue LED die (451.8 nm), G3161 (530 nm) and O5446 (586 nm) phosphors (Intematix Corporation), the AlGaInP red LED (λR = 627.2 nm and Φ = 66.2 lm at IF = 350 mA) and the InGaN blue LED (λB = 464.9 nm, Φ = 27.1 lm at IF = 350 mA) are fabricated in our laboratory. The SPDs, the luminous flux and the input power of the PC LED, blue and red LEDs at drive currents of 30~350 mA are measured by an automated photometric/radiometric measurement setup and a power meter at an ambient temperature (Ta) of 25°C. The real SPDs of the PC LED, blue and red LEDs at drive current of 350 mA are shown in Fig. 1. The numbers of LED (N), drive currents (IF) according to requirements of CCT, CRI, R9 and input power (Pin) of the PC/R/B LED cluster can be predicted by using He-Zheng model [7]. The real PC/R/B LED cluster consists of four PC LEDs, three red LEDs and two blue LEDs. The color rendering property and luminous efficacy of the real PC/R/B LED cluster at an ambient temperature (Ta) of 25°C are shown in Table 2 according to the predicted drive current (IF) of each LED at different CCTs. The measured SPDs of the real PC/R/B LED cluster at different CCTs are shown in Fig. 3 . The chromaticities of real PC/R/B LED cluster at CCTs of 2722 K, 3040 K, 3514 K, 4024 K, 4574 K, 4968 K, 5719 K and 6464 K are shown in Fig. 2. The experimental results show that the real PC/R/B LED cluster can realize the CCT tunable white-light with CRIs of 90~96, R9s of 90~96, CQSs of 89~94, LERs of 303~358 lm/W, and LEs of 105~119 lm/W at CCTs of 2722 K to 6464 K. Furthermore, their special CRIs of R13 and R15 corresponding to the colors of the skin on the face of European and Chinese women are also very high. Both R13 and R15 are especially important for interior lighting.

Tables Icon

Table 2. Color rendering property and luminous efficacy of the real PC/R/B LED cluster at Ta = 25°C according to the predicted drive current (IF) of each LED at different CCTs.

 figure: Fig. 3

Fig. 3 Measured SPDs of the real PC/R/B LED cluster at different CCTs

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4. Effects of the deviations from peak emission wavelengths of LEDs

In order to achieve the PC/R/B LED cluster with high optical performance, we simulate the effect of the deviations from peak wavelengths of the blue LED die, red LED and blue LED in the real PC/R/B LED cluster. The changes in CRI, R9 and CCT of the PC/R/B LED cluster caused by the peak wavelength shifts of blue LED die, red LED and blue LED are shown in Figs. 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , and 12 , respectively. The results show that CRI, R9 and CCT of the PC/R/B LED cluster are more sensitive to the peak wavelength shifts of red and blue LED. According to the results of this simulation, the deviation of the peak wavelength should be less than ± 5 nm for blue LED die, ± 1 nm for red LED, and ± 2 nm for blue LED to achieve the PC/R/B LED cluster with high optical performance.

 figure: Fig. 4

Fig. 4 Changes in CRI of the PC/R/B LED cluster caused by the peak wavelength shift of blue LED die

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 figure: Fig. 5

Fig. 5 Changes in R9 of the PC/R/B LED cluster caused by the peak wavelength shift of blue LED die

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 figure: Fig. 6

Fig. 6 Changes in CCT of the PC/R/B LED cluster caused by the peak wavelength shift of blue LED die

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 figure: Fig. 7

Fig. 7 Changes in CRI of the PC/R/B LED cluster caused by the peak wavelength shift of red LED

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 figure: Fig. 8

Fig. 8 Changes in R9 of the PC/R/B LED cluster caused by the peak wavelength shift of red LED

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 figure: Fig. 9

Fig. 9 Changes in CCT of the PC/R/B LED cluster caused by the peak wavelength shift of red LED

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 figure: Fig. 10

Fig. 10 Changes in CRI of the PC/R/B LED cluster caused by the peak wavelength shift of blue LED

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 figure: Fig. 11

Fig. 11 Changes in R9 of PC/R/B LED cluster caused by the peak wavelength shift of blue LED

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 figure: Fig. 12

Fig. 12 Changes in CCT of the PC/R/B LED cluster caused by the peak wavelength shift of blue LED

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5.Conclusion

The optimal CCT tunable PC/R/B LED cluster consists of the AlGaInP red LED (628 nm), the InGaN blue LED (465 nm) and the PC LED (x = 0.3717, y = 0.4803) packaged by combining silicate green (530 nm) and orange (586 nm) phosphors with the InGaN blue LED die (452 nm). It could realize CCT tunable white-light with CRIs of 90~96, R9s of 91~96, CQSs of 90~95 and LERs of 301~357 lm/W at CCTs of 2700 K to 6500 K. The real PC /R/B LED cluster consisting of four PC LEDs (x = 0.3715, y = 0.4851 and LE = 127.6 lm/W at IF = 350 mA) with the InGaN blue LED die (451.8 nm), G3161 (530 nm) and O5446 (586 nm) phosphors (Intematix Corporation), three AlGaInP red LEDs (λR = 627.2 nm and Φ = 66.2 lm at IF = 350 mA) and two InGaN blue LEDs (λB = 464.9 nm, Φ = 27.1 lm at IF = 350 mA) can realize the CCT tunable white-light with CRIs of 90~96, R9s of 90~96, CQSs of 89~94, LERs of 303~358 lm/W, and LEs of 105~119 lm/W at CCTs of 2722 K to 6464 K. The deviation of the peak wavelength should be less than ± 5 nm for blue LED die, ± 1 nm for red LED, and ± 2 nm for blue LED to achieve the PC/R/B LED cluster with high optical performance.

Acknowledgments

This work was supported by Shanghai Science and Technology Committee (No.09DZ1141100) and the National “ITER” Project of Ministry of Science and Technology of P. R. China (No.2009GB107006 and No.2010GB107003).

References and links

1. S. Hattar, H. W. Liao, M. Takao, D. M. Berson, and K. W. Yau, “Melanopsin-containing retinal ganglion cells: architecture, projections, and intrinsic photosensitivity,” Science 295(5557), 1065–1070 (2002). [CrossRef]   [PubMed]  

2. D. M. Berson, F. A. Dunn, and M. Takao, “Phototransduction by retinal ganglion cells that set the circadian clock,” Science 295(5557), 1070–1073 (2002). [CrossRef]   [PubMed]  

3. D. E. Blask, R. T. Dauchy, L. A. Sauer, J. A. Krause, and G. C. Brainard, “Growth and fatty acid metabolism of human breast cancer (MCF-7) xenografts in nude rats: impact of constant light-induced nocturnal melatonin suppression,” Breast Cancer Res. Treat. 79(3), 313–320 (2003). [CrossRef]   [PubMed]  

4. E. F. Schubert and J. K. Kim, “Solid-state light sources getting smart,” Science 308(5726), 1274–1278 (2005). [CrossRef]   [PubMed]  

5. International Commission on Illumination, Method of Measuring and Specifying Colour Rendering Properties of Light Sources (Commission Internationale de l'Éclairage, Vienna, Austria, 1995).

6. I. Speier and M. Salsbury, “Color temperature tunable white light LED system,” Proc. SPIE 6337, 63371F, 63371F-12 (2006). [CrossRef]  

7. G. X. He and L. H. Zheng, “Color temperature tunable white-light light-emitting diode clusters with high color rendering index,” Appl. Opt. 49(24), 4670–4676 (2010). [CrossRef]   [PubMed]  

8. G. X. He and L. H. Zheng, “White-light LED clusters with high color rendering,” Opt. Lett. 35(17), 2955–2957 (2010). [CrossRef]   [PubMed]  

9. M. C. Chien and C. H. Tien, “Cluster LEDs mixing optimization by lens design techniques,” Opt. Express 19(S4Suppl 4), A804–A817 (2011). [CrossRef]   [PubMed]  

10. M. C. Chien and C. H. Tien, “Multispectral mixing scheme for LED clusters with extended operational temperature window,” Opt. Express 20(S2Suppl 2), A245–A254 (2012). [CrossRef]   [PubMed]  

11. N. Narendran and L. Deng, “Color rendering properties of LED light sources,” Proc. SPIE 4776, 61–67 (2002). [CrossRef]  

12. N. Sándor and J. Schanda, “Visual colour rendering based on colour difference evaluations,” Lighting Res. Tech. 38(3), 225–239 (2006). [CrossRef]  

13. CIE, “TC 1-62: Color Rendering of White LED Light Sources,” in CIE 177:2007 (CIE, Vienna, Austria, 2007).

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

15. A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, R. Gaska, and M. S. Shur, “Optimization of white polychromatric semiconductor lamps,” Appl. Phys. Lett. 80(2), 234–236 (2002). [CrossRef]  

16. S. Chhajed, Y. Xi, Y. L. Li, T. Gessmann, and E. F. Schubert, “Influence of junction temperature on chromaticity and color-rendering properties of trichromatic white-light sources based on light-emitting diodes,” J. Appl. Phys. 97(5), 054506 (2005). [CrossRef]  

17. A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, H. Vaitkevičius, and M. S. Shur, “Rendering a color palette by light-emitting diodes,” Appl. Phys. Lett. 93(2), 021109 (2008). [CrossRef]  

18. A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, H. Vaitkevicius, and M. S. Shur, “Spectral optimization of phosphor-conversion light-emitting diodes for ultimate color rendering,” Appl. Phys. Lett. 93(5), 051115 (2008). [CrossRef]  

19. A. Zukauskas, R. Vaicekauskas, and M. S. Shur, “Solid-state lamps with optimized color saturation ability,” Opt. Express 18(3), 2287–2295 (2010). [CrossRef]   [PubMed]  

20. G. X. He and H. F. Yan, “Optimal spectra of the phosphor-coated white LEDs with excellent color rendering property and high luminous efficacy of radiation,” Opt. Express 19(3), 2519–2529 (2011). [CrossRef]   [PubMed]  

21. G. X. He, J. Xu, and H. F. Yan, “Spectral optimization of warm-white light-emitting diode lamp with both color rendering index (CRI) and special CRI of R9 above 90,” AIP Advances 1(3), 032160 (2011). [CrossRef]  

22. P. Zhong, G. X. He, and M. H. Zhang, “Optimal spectra of white light-emitting diodes using quantum dot nanophosphors,” Opt. Express 20(8), 9122–9134 (2012). [CrossRef]   [PubMed]  

23. J. Worthey, “Color rendering: asking the questions,” Color Res. Appl. 28(6), 403–412 (2003). [CrossRef]  

24. K. Hashimoto and Y. Nayatani, “Visual clarity and feeling of contrast,” Color Res. Appl. 19(3), 171–185 (1994). [CrossRef]  

25. I. Moreno and U. Contreras, “Color distribution from multicolor LED arrays,” Opt. Express 15(6), 3607–3618 (2007). [CrossRef]   [PubMed]  

26. H. Eskandari and C. D. Geiger, “A fast Pareto genetic algorithm approach for solving expensive multiobjective optimization problems,” J. Heuristics 14(3), 203–241 (2008). [CrossRef]  

References

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  1. S. Hattar, H. W. Liao, M. Takao, D. M. Berson, and K. W. Yau, “Melanopsin-containing retinal ganglion cells: architecture, projections, and intrinsic photosensitivity,” Science 295(5557), 1065–1070 (2002).
    [Crossref] [PubMed]
  2. D. M. Berson, F. A. Dunn, and M. Takao, “Phototransduction by retinal ganglion cells that set the circadian clock,” Science 295(5557), 1070–1073 (2002).
    [Crossref] [PubMed]
  3. D. E. Blask, R. T. Dauchy, L. A. Sauer, J. A. Krause, and G. C. Brainard, “Growth and fatty acid metabolism of human breast cancer (MCF-7) xenografts in nude rats: impact of constant light-induced nocturnal melatonin suppression,” Breast Cancer Res. Treat. 79(3), 313–320 (2003).
    [Crossref] [PubMed]
  4. E. F. Schubert and J. K. Kim, “Solid-state light sources getting smart,” Science 308(5726), 1274–1278 (2005).
    [Crossref] [PubMed]
  5. International Commission on Illumination, Method of Measuring and Specifying Colour Rendering Properties of Light Sources (Commission Internationale de l'Éclairage, Vienna, Austria, 1995).
  6. I. Speier and M. Salsbury, “Color temperature tunable white light LED system,” Proc. SPIE 6337, 63371F, 63371F-12 (2006).
    [Crossref]
  7. G. X. He and L. H. Zheng, “Color temperature tunable white-light light-emitting diode clusters with high color rendering index,” Appl. Opt. 49(24), 4670–4676 (2010).
    [Crossref] [PubMed]
  8. G. X. He and L. H. Zheng, “White-light LED clusters with high color rendering,” Opt. Lett. 35(17), 2955–2957 (2010).
    [Crossref] [PubMed]
  9. M. C. Chien and C. H. Tien, “Cluster LEDs mixing optimization by lens design techniques,” Opt. Express 19(S4Suppl 4), A804–A817 (2011).
    [Crossref] [PubMed]
  10. M. C. Chien and C. H. Tien, “Multispectral mixing scheme for LED clusters with extended operational temperature window,” Opt. Express 20(S2Suppl 2), A245–A254 (2012).
    [Crossref] [PubMed]
  11. N. Narendran and L. Deng, “Color rendering properties of LED light sources,” Proc. SPIE 4776, 61–67 (2002).
    [Crossref]
  12. N. Sándor and J. Schanda, “Visual colour rendering based on colour difference evaluations,” Lighting Res. Tech. 38(3), 225–239 (2006).
    [Crossref]
  13. CIE, “TC 1-62: Color Rendering of White LED Light Sources,” in CIE 177:2007 (CIE, Vienna, Austria, 2007).
  14. W. Davis and Y. Ohno, “Color qulity scale,” Opt. Eng. 49(3), 033602 (2010).
    [Crossref]
  15. A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, R. Gaska, and M. S. Shur, “Optimization of white polychromatric semiconductor lamps,” Appl. Phys. Lett. 80(2), 234–236 (2002).
    [Crossref]
  16. S. Chhajed, Y. Xi, Y. L. Li, T. Gessmann, and E. F. Schubert, “Influence of junction temperature on chromaticity and color-rendering properties of trichromatic white-light sources based on light-emitting diodes,” J. Appl. Phys. 97(5), 054506 (2005).
    [Crossref]
  17. A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, H. Vaitkevičius, and M. S. Shur, “Rendering a color palette by light-emitting diodes,” Appl. Phys. Lett. 93(2), 021109 (2008).
    [Crossref]
  18. A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, H. Vaitkevicius, and M. S. Shur, “Spectral optimization of phosphor-conversion light-emitting diodes for ultimate color rendering,” Appl. Phys. Lett. 93(5), 051115 (2008).
    [Crossref]
  19. A. Zukauskas, R. Vaicekauskas, and M. S. Shur, “Solid-state lamps with optimized color saturation ability,” Opt. Express 18(3), 2287–2295 (2010).
    [Crossref] [PubMed]
  20. G. X. He and H. F. Yan, “Optimal spectra of the phosphor-coated white LEDs with excellent color rendering property and high luminous efficacy of radiation,” Opt. Express 19(3), 2519–2529 (2011).
    [Crossref] [PubMed]
  21. G. X. He, J. Xu, and H. F. Yan, “Spectral optimization of warm-white light-emitting diode lamp with both color rendering index (CRI) and special CRI of R9 above 90,” AIP Advances 1(3), 032160 (2011).
    [Crossref]
  22. P. Zhong, G. X. He, and M. H. Zhang, “Optimal spectra of white light-emitting diodes using quantum dot nanophosphors,” Opt. Express 20(8), 9122–9134 (2012).
    [Crossref] [PubMed]
  23. J. Worthey, “Color rendering: asking the questions,” Color Res. Appl. 28(6), 403–412 (2003).
    [Crossref]
  24. K. Hashimoto and Y. Nayatani, “Visual clarity and feeling of contrast,” Color Res. Appl. 19(3), 171–185 (1994).
    [Crossref]
  25. I. Moreno and U. Contreras, “Color distribution from multicolor LED arrays,” Opt. Express 15(6), 3607–3618 (2007).
    [Crossref] [PubMed]
  26. H. Eskandari and C. D. Geiger, “A fast Pareto genetic algorithm approach for solving expensive multiobjective optimization problems,” J. Heuristics 14(3), 203–241 (2008).
    [Crossref]

2012 (2)

2011 (3)

2010 (4)

2008 (3)

H. Eskandari and C. D. Geiger, “A fast Pareto genetic algorithm approach for solving expensive multiobjective optimization problems,” J. Heuristics 14(3), 203–241 (2008).
[Crossref]

A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, H. Vaitkevičius, and M. S. Shur, “Rendering a color palette by light-emitting diodes,” Appl. Phys. Lett. 93(2), 021109 (2008).
[Crossref]

A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, H. Vaitkevicius, and M. S. Shur, “Spectral optimization of phosphor-conversion light-emitting diodes for ultimate color rendering,” Appl. Phys. Lett. 93(5), 051115 (2008).
[Crossref]

2007 (1)

2006 (2)

N. Sándor and J. Schanda, “Visual colour rendering based on colour difference evaluations,” Lighting Res. Tech. 38(3), 225–239 (2006).
[Crossref]

I. Speier and M. Salsbury, “Color temperature tunable white light LED system,” Proc. SPIE 6337, 63371F, 63371F-12 (2006).
[Crossref]

2005 (2)

E. F. Schubert and J. K. Kim, “Solid-state light sources getting smart,” Science 308(5726), 1274–1278 (2005).
[Crossref] [PubMed]

S. Chhajed, Y. Xi, Y. L. Li, T. Gessmann, and E. F. Schubert, “Influence of junction temperature on chromaticity and color-rendering properties of trichromatic white-light sources based on light-emitting diodes,” J. Appl. Phys. 97(5), 054506 (2005).
[Crossref]

2003 (2)

D. E. Blask, R. T. Dauchy, L. A. Sauer, J. A. Krause, and G. C. Brainard, “Growth and fatty acid metabolism of human breast cancer (MCF-7) xenografts in nude rats: impact of constant light-induced nocturnal melatonin suppression,” Breast Cancer Res. Treat. 79(3), 313–320 (2003).
[Crossref] [PubMed]

J. Worthey, “Color rendering: asking the questions,” Color Res. Appl. 28(6), 403–412 (2003).
[Crossref]

2002 (4)

S. Hattar, H. W. Liao, M. Takao, D. M. Berson, and K. W. Yau, “Melanopsin-containing retinal ganglion cells: architecture, projections, and intrinsic photosensitivity,” Science 295(5557), 1065–1070 (2002).
[Crossref] [PubMed]

D. M. Berson, F. A. Dunn, and M. Takao, “Phototransduction by retinal ganglion cells that set the circadian clock,” Science 295(5557), 1070–1073 (2002).
[Crossref] [PubMed]

A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, R. Gaska, and M. S. Shur, “Optimization of white polychromatric semiconductor lamps,” Appl. Phys. Lett. 80(2), 234–236 (2002).
[Crossref]

N. Narendran and L. Deng, “Color rendering properties of LED light sources,” Proc. SPIE 4776, 61–67 (2002).
[Crossref]

1994 (1)

K. Hashimoto and Y. Nayatani, “Visual clarity and feeling of contrast,” Color Res. Appl. 19(3), 171–185 (1994).
[Crossref]

Berson, D. M.

S. Hattar, H. W. Liao, M. Takao, D. M. Berson, and K. W. Yau, “Melanopsin-containing retinal ganglion cells: architecture, projections, and intrinsic photosensitivity,” Science 295(5557), 1065–1070 (2002).
[Crossref] [PubMed]

D. M. Berson, F. A. Dunn, and M. Takao, “Phototransduction by retinal ganglion cells that set the circadian clock,” Science 295(5557), 1070–1073 (2002).
[Crossref] [PubMed]

Blask, D. E.

D. E. Blask, R. T. Dauchy, L. A. Sauer, J. A. Krause, and G. C. Brainard, “Growth and fatty acid metabolism of human breast cancer (MCF-7) xenografts in nude rats: impact of constant light-induced nocturnal melatonin suppression,” Breast Cancer Res. Treat. 79(3), 313–320 (2003).
[Crossref] [PubMed]

Brainard, G. C.

D. E. Blask, R. T. Dauchy, L. A. Sauer, J. A. Krause, and G. C. Brainard, “Growth and fatty acid metabolism of human breast cancer (MCF-7) xenografts in nude rats: impact of constant light-induced nocturnal melatonin suppression,” Breast Cancer Res. Treat. 79(3), 313–320 (2003).
[Crossref] [PubMed]

Chhajed, S.

S. Chhajed, Y. Xi, Y. L. Li, T. Gessmann, and E. F. Schubert, “Influence of junction temperature on chromaticity and color-rendering properties of trichromatic white-light sources based on light-emitting diodes,” J. Appl. Phys. 97(5), 054506 (2005).
[Crossref]

Chien, M. C.

Contreras, U.

Dauchy, R. T.

D. E. Blask, R. T. Dauchy, L. A. Sauer, J. A. Krause, and G. C. Brainard, “Growth and fatty acid metabolism of human breast cancer (MCF-7) xenografts in nude rats: impact of constant light-induced nocturnal melatonin suppression,” Breast Cancer Res. Treat. 79(3), 313–320 (2003).
[Crossref] [PubMed]

Davis, W.

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

Deng, L.

N. Narendran and L. Deng, “Color rendering properties of LED light sources,” Proc. SPIE 4776, 61–67 (2002).
[Crossref]

Dunn, F. A.

D. M. Berson, F. A. Dunn, and M. Takao, “Phototransduction by retinal ganglion cells that set the circadian clock,” Science 295(5557), 1070–1073 (2002).
[Crossref] [PubMed]

Eskandari, H.

H. Eskandari and C. D. Geiger, “A fast Pareto genetic algorithm approach for solving expensive multiobjective optimization problems,” J. Heuristics 14(3), 203–241 (2008).
[Crossref]

Gaska, R.

A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, R. Gaska, and M. S. Shur, “Optimization of white polychromatric semiconductor lamps,” Appl. Phys. Lett. 80(2), 234–236 (2002).
[Crossref]

Geiger, C. D.

H. Eskandari and C. D. Geiger, “A fast Pareto genetic algorithm approach for solving expensive multiobjective optimization problems,” J. Heuristics 14(3), 203–241 (2008).
[Crossref]

Gessmann, T.

S. Chhajed, Y. Xi, Y. L. Li, T. Gessmann, and E. F. Schubert, “Influence of junction temperature on chromaticity and color-rendering properties of trichromatic white-light sources based on light-emitting diodes,” J. Appl. Phys. 97(5), 054506 (2005).
[Crossref]

Hashimoto, K.

K. Hashimoto and Y. Nayatani, “Visual clarity and feeling of contrast,” Color Res. Appl. 19(3), 171–185 (1994).
[Crossref]

Hattar, S.

S. Hattar, H. W. Liao, M. Takao, D. M. Berson, and K. W. Yau, “Melanopsin-containing retinal ganglion cells: architecture, projections, and intrinsic photosensitivity,” Science 295(5557), 1065–1070 (2002).
[Crossref] [PubMed]

He, G. X.

Ivanauskas, F.

A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, H. Vaitkevičius, and M. S. Shur, “Rendering a color palette by light-emitting diodes,” Appl. Phys. Lett. 93(2), 021109 (2008).
[Crossref]

A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, H. Vaitkevicius, and M. S. Shur, “Spectral optimization of phosphor-conversion light-emitting diodes for ultimate color rendering,” Appl. Phys. Lett. 93(5), 051115 (2008).
[Crossref]

A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, R. Gaska, and M. S. Shur, “Optimization of white polychromatric semiconductor lamps,” Appl. Phys. Lett. 80(2), 234–236 (2002).
[Crossref]

Kim, J. K.

E. F. Schubert and J. K. Kim, “Solid-state light sources getting smart,” Science 308(5726), 1274–1278 (2005).
[Crossref] [PubMed]

Krause, J. A.

D. E. Blask, R. T. Dauchy, L. A. Sauer, J. A. Krause, and G. C. Brainard, “Growth and fatty acid metabolism of human breast cancer (MCF-7) xenografts in nude rats: impact of constant light-induced nocturnal melatonin suppression,” Breast Cancer Res. Treat. 79(3), 313–320 (2003).
[Crossref] [PubMed]

Li, Y. L.

S. Chhajed, Y. Xi, Y. L. Li, T. Gessmann, and E. F. Schubert, “Influence of junction temperature on chromaticity and color-rendering properties of trichromatic white-light sources based on light-emitting diodes,” J. Appl. Phys. 97(5), 054506 (2005).
[Crossref]

Liao, H. W.

S. Hattar, H. W. Liao, M. Takao, D. M. Berson, and K. W. Yau, “Melanopsin-containing retinal ganglion cells: architecture, projections, and intrinsic photosensitivity,” Science 295(5557), 1065–1070 (2002).
[Crossref] [PubMed]

Moreno, I.

Narendran, N.

N. Narendran and L. Deng, “Color rendering properties of LED light sources,” Proc. SPIE 4776, 61–67 (2002).
[Crossref]

Nayatani, Y.

K. Hashimoto and Y. Nayatani, “Visual clarity and feeling of contrast,” Color Res. Appl. 19(3), 171–185 (1994).
[Crossref]

Ohno, Y.

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

Salsbury, M.

I. Speier and M. Salsbury, “Color temperature tunable white light LED system,” Proc. SPIE 6337, 63371F, 63371F-12 (2006).
[Crossref]

Sándor, N.

N. Sándor and J. Schanda, “Visual colour rendering based on colour difference evaluations,” Lighting Res. Tech. 38(3), 225–239 (2006).
[Crossref]

Sauer, L. A.

D. E. Blask, R. T. Dauchy, L. A. Sauer, J. A. Krause, and G. C. Brainard, “Growth and fatty acid metabolism of human breast cancer (MCF-7) xenografts in nude rats: impact of constant light-induced nocturnal melatonin suppression,” Breast Cancer Res. Treat. 79(3), 313–320 (2003).
[Crossref] [PubMed]

Schanda, J.

N. Sándor and J. Schanda, “Visual colour rendering based on colour difference evaluations,” Lighting Res. Tech. 38(3), 225–239 (2006).
[Crossref]

Schubert, E. F.

E. F. Schubert and J. K. Kim, “Solid-state light sources getting smart,” Science 308(5726), 1274–1278 (2005).
[Crossref] [PubMed]

S. Chhajed, Y. Xi, Y. L. Li, T. Gessmann, and E. F. Schubert, “Influence of junction temperature on chromaticity and color-rendering properties of trichromatic white-light sources based on light-emitting diodes,” J. Appl. Phys. 97(5), 054506 (2005).
[Crossref]

Shur, M. S.

A. Zukauskas, R. Vaicekauskas, and M. S. Shur, “Solid-state lamps with optimized color saturation ability,” Opt. Express 18(3), 2287–2295 (2010).
[Crossref] [PubMed]

A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, H. Vaitkevicius, and M. S. Shur, “Spectral optimization of phosphor-conversion light-emitting diodes for ultimate color rendering,” Appl. Phys. Lett. 93(5), 051115 (2008).
[Crossref]

A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, H. Vaitkevičius, and M. S. Shur, “Rendering a color palette by light-emitting diodes,” Appl. Phys. Lett. 93(2), 021109 (2008).
[Crossref]

A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, R. Gaska, and M. S. Shur, “Optimization of white polychromatric semiconductor lamps,” Appl. Phys. Lett. 80(2), 234–236 (2002).
[Crossref]

Speier, I.

I. Speier and M. Salsbury, “Color temperature tunable white light LED system,” Proc. SPIE 6337, 63371F, 63371F-12 (2006).
[Crossref]

Takao, M.

D. M. Berson, F. A. Dunn, and M. Takao, “Phototransduction by retinal ganglion cells that set the circadian clock,” Science 295(5557), 1070–1073 (2002).
[Crossref] [PubMed]

S. Hattar, H. W. Liao, M. Takao, D. M. Berson, and K. W. Yau, “Melanopsin-containing retinal ganglion cells: architecture, projections, and intrinsic photosensitivity,” Science 295(5557), 1065–1070 (2002).
[Crossref] [PubMed]

Tien, C. H.

Vaicekauskas, R.

A. Zukauskas, R. Vaicekauskas, and M. S. Shur, “Solid-state lamps with optimized color saturation ability,” Opt. Express 18(3), 2287–2295 (2010).
[Crossref] [PubMed]

A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, H. Vaitkevičius, and M. S. Shur, “Rendering a color palette by light-emitting diodes,” Appl. Phys. Lett. 93(2), 021109 (2008).
[Crossref]

A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, H. Vaitkevicius, and M. S. Shur, “Spectral optimization of phosphor-conversion light-emitting diodes for ultimate color rendering,” Appl. Phys. Lett. 93(5), 051115 (2008).
[Crossref]

A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, R. Gaska, and M. S. Shur, “Optimization of white polychromatric semiconductor lamps,” Appl. Phys. Lett. 80(2), 234–236 (2002).
[Crossref]

Vaitkevicius, H.

A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, H. Vaitkevicius, and M. S. Shur, “Spectral optimization of phosphor-conversion light-emitting diodes for ultimate color rendering,” Appl. Phys. Lett. 93(5), 051115 (2008).
[Crossref]

A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, H. Vaitkevičius, and M. S. Shur, “Rendering a color palette by light-emitting diodes,” Appl. Phys. Lett. 93(2), 021109 (2008).
[Crossref]

Worthey, J.

J. Worthey, “Color rendering: asking the questions,” Color Res. Appl. 28(6), 403–412 (2003).
[Crossref]

Xi, Y.

S. Chhajed, Y. Xi, Y. L. Li, T. Gessmann, and E. F. Schubert, “Influence of junction temperature on chromaticity and color-rendering properties of trichromatic white-light sources based on light-emitting diodes,” J. Appl. Phys. 97(5), 054506 (2005).
[Crossref]

Xu, J.

G. X. He, J. Xu, and H. F. Yan, “Spectral optimization of warm-white light-emitting diode lamp with both color rendering index (CRI) and special CRI of R9 above 90,” AIP Advances 1(3), 032160 (2011).
[Crossref]

Yan, H. F.

G. X. He, J. Xu, and H. F. Yan, “Spectral optimization of warm-white light-emitting diode lamp with both color rendering index (CRI) and special CRI of R9 above 90,” AIP Advances 1(3), 032160 (2011).
[Crossref]

G. X. He and H. F. Yan, “Optimal spectra of the phosphor-coated white LEDs with excellent color rendering property and high luminous efficacy of radiation,” Opt. Express 19(3), 2519–2529 (2011).
[Crossref] [PubMed]

Yau, K. W.

S. Hattar, H. W. Liao, M. Takao, D. M. Berson, and K. W. Yau, “Melanopsin-containing retinal ganglion cells: architecture, projections, and intrinsic photosensitivity,” Science 295(5557), 1065–1070 (2002).
[Crossref] [PubMed]

Zhang, M. H.

Zheng, L. H.

Zhong, P.

Zukauskas, A.

A. Zukauskas, R. Vaicekauskas, and M. S. Shur, “Solid-state lamps with optimized color saturation ability,” Opt. Express 18(3), 2287–2295 (2010).
[Crossref] [PubMed]

A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, H. Vaitkevicius, and M. S. Shur, “Spectral optimization of phosphor-conversion light-emitting diodes for ultimate color rendering,” Appl. Phys. Lett. 93(5), 051115 (2008).
[Crossref]

A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, H. Vaitkevičius, and M. S. Shur, “Rendering a color palette by light-emitting diodes,” Appl. Phys. Lett. 93(2), 021109 (2008).
[Crossref]

A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, R. Gaska, and M. S. Shur, “Optimization of white polychromatric semiconductor lamps,” Appl. Phys. Lett. 80(2), 234–236 (2002).
[Crossref]

AIP Advances (1)

G. X. He, J. Xu, and H. F. Yan, “Spectral optimization of warm-white light-emitting diode lamp with both color rendering index (CRI) and special CRI of R9 above 90,” AIP Advances 1(3), 032160 (2011).
[Crossref]

Appl. Opt. (1)

Appl. Phys. Lett. (3)

A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, H. Vaitkevičius, and M. S. Shur, “Rendering a color palette by light-emitting diodes,” Appl. Phys. Lett. 93(2), 021109 (2008).
[Crossref]

A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, H. Vaitkevicius, and M. S. Shur, “Spectral optimization of phosphor-conversion light-emitting diodes for ultimate color rendering,” Appl. Phys. Lett. 93(5), 051115 (2008).
[Crossref]

A. Zukauskas, R. Vaicekauskas, F. Ivanauskas, R. Gaska, and M. S. Shur, “Optimization of white polychromatric semiconductor lamps,” Appl. Phys. Lett. 80(2), 234–236 (2002).
[Crossref]

Breast Cancer Res. Treat. (1)

D. E. Blask, R. T. Dauchy, L. A. Sauer, J. A. Krause, and G. C. Brainard, “Growth and fatty acid metabolism of human breast cancer (MCF-7) xenografts in nude rats: impact of constant light-induced nocturnal melatonin suppression,” Breast Cancer Res. Treat. 79(3), 313–320 (2003).
[Crossref] [PubMed]

Color Res. Appl. (2)

J. Worthey, “Color rendering: asking the questions,” Color Res. Appl. 28(6), 403–412 (2003).
[Crossref]

K. Hashimoto and Y. Nayatani, “Visual clarity and feeling of contrast,” Color Res. Appl. 19(3), 171–185 (1994).
[Crossref]

J. Appl. Phys. (1)

S. Chhajed, Y. Xi, Y. L. Li, T. Gessmann, and E. F. Schubert, “Influence of junction temperature on chromaticity and color-rendering properties of trichromatic white-light sources based on light-emitting diodes,” J. Appl. Phys. 97(5), 054506 (2005).
[Crossref]

J. Heuristics (1)

H. Eskandari and C. D. Geiger, “A fast Pareto genetic algorithm approach for solving expensive multiobjective optimization problems,” J. Heuristics 14(3), 203–241 (2008).
[Crossref]

Lighting Res. Tech. (1)

N. Sándor and J. Schanda, “Visual colour rendering based on colour difference evaluations,” Lighting Res. Tech. 38(3), 225–239 (2006).
[Crossref]

Opt. Eng. (1)

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

Opt. Express (6)

Opt. Lett. (1)

Proc. SPIE (2)

N. Narendran and L. Deng, “Color rendering properties of LED light sources,” Proc. SPIE 4776, 61–67 (2002).
[Crossref]

I. Speier and M. Salsbury, “Color temperature tunable white light LED system,” Proc. SPIE 6337, 63371F, 63371F-12 (2006).
[Crossref]

Science (3)

E. F. Schubert and J. K. Kim, “Solid-state light sources getting smart,” Science 308(5726), 1274–1278 (2005).
[Crossref] [PubMed]

S. Hattar, H. W. Liao, M. Takao, D. M. Berson, and K. W. Yau, “Melanopsin-containing retinal ganglion cells: architecture, projections, and intrinsic photosensitivity,” Science 295(5557), 1065–1070 (2002).
[Crossref] [PubMed]

D. M. Berson, F. A. Dunn, and M. Takao, “Phototransduction by retinal ganglion cells that set the circadian clock,” Science 295(5557), 1070–1073 (2002).
[Crossref] [PubMed]

Other (2)

International Commission on Illumination, Method of Measuring and Specifying Colour Rendering Properties of Light Sources (Commission Internationale de l'Éclairage, Vienna, Austria, 1995).

CIE, “TC 1-62: Color Rendering of White LED Light Sources,” in CIE 177:2007 (CIE, Vienna, Austria, 2007).

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Figures (12)

Fig. 1
Fig. 1 Optimal and real relative SPDs of PC, red and blue LEDs
Fig. 2
Fig. 2 The PC/R/B LED cluster provides a triangular color gamut that encompasses the Planckian locus from 2222 K to 100000 K, so it is possible to achieve CCT tunability. Also showing the chromaticities of real PC/R/B LED cluster at CCTs of 2722 K, 3040 K, 3514 K, 4024 K, 4574 K, 4968 K, 5719 K and 6464 K.
Fig. 3
Fig. 3 Measured SPDs of the real PC/R/B LED cluster at different CCTs
Fig. 4
Fig. 4 Changes in CRI of the PC/R/B LED cluster caused by the peak wavelength shift of blue LED die
Fig. 5
Fig. 5 Changes in R9 of the PC/R/B LED cluster caused by the peak wavelength shift of blue LED die
Fig. 6
Fig. 6 Changes in CCT of the PC/R/B LED cluster caused by the peak wavelength shift of blue LED die
Fig. 7
Fig. 7 Changes in CRI of the PC/R/B LED cluster caused by the peak wavelength shift of red LED
Fig. 8
Fig. 8 Changes in R9 of the PC/R/B LED cluster caused by the peak wavelength shift of red LED
Fig. 9
Fig. 9 Changes in CCT of the PC/R/B LED cluster caused by the peak wavelength shift of red LED
Fig. 10
Fig. 10 Changes in CRI of the PC/R/B LED cluster caused by the peak wavelength shift of blue LED
Fig. 11
Fig. 11 Changes in R9 of PC/R/B LED cluster caused by the peak wavelength shift of blue LED
Fig. 12
Fig. 12 Changes in CCT of the PC/R/B LED cluster caused by the peak wavelength shift of blue LED

Tables (2)

Tables Icon

Table 1 CRI, R9, CQS and LER of the optimal PC/R/B LED cluster at CCTs of 2700 K to 6500 K.

Tables Icon

Table 2 Color rendering property and luminous efficacy of the real PC/R/B LED cluster at Ta = 25°C according to the predicted drive current (IF) of each LED at different CCTs.

Equations (3)

Equations on this page are rendered with MathJax. Learn more.

S PC/R/B (λ)= k PC S PC (λ, λ b , λ g , λ or )+ k R S R (λ, λ R )+ k B S(λ, λ B )
S PC (λ, λ b , λ g , λ or )= q b S b (λ, λ b )+ q g S g (λ, λ g )+ q or S or (λ, λ or )
F( λ b , λ g , λ or , λ R , λ B , q b , q g , q or )= i=1 8 LE R i (i=1,2,3 ,8) (under conditions of CRI i 90 and R9 i 90 with dC0.0054)

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