Abstract

A model for LED spectra at different drive currents is established. The simulation program of color rendering of a white-light LED cluster is developed according to the principle of additive color mixtures. The program can predict not only the spectral power distribution, chromaticity coordinates, correlated color temperature (CCT), and color rendering index (CRI), but also the drive currents of LEDs, luminous flux, input power, and luminous efficacy of white-light LED clusters. Three types of CCT tunable white-light LED clusters [warm-white/red/green/blue (WW/R/G/B), neutral-white (NW)/R/G/B, and cool-white/R/amber/G clusters] with high CRI are found by simulation analysis and realized in our laboratory. The experimental results show that the WW/R/G/B cluster can realize CCT tunable white light with high CRIs (above 90) but lower luminous efficacies (below 65lm/W), and that the NW/R/G/B cluster can realize CCT tunable white light with high CRIs (above 86), as well as high luminous efficacies (above 64lm/W).

© 2010 Optical Society of America

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References

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  1. I. Speier and M. Salsbury, “Color temperature tunable white light LED system,” Proc. SPIE 6337, 63371F (2006).
    [CrossRef]
  2. Y. Ohno, “Color rendering and luminous efficacy of white LED spectra,” Proc. SPIE 5530, 88–98 (2004).
    [CrossRef]
  3. 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, 054506 (2005).
    [CrossRef]
  4. K. Man and I. Ashdown, “Accurate colorimetric feedback for RGB LED clusters,” Proc. SPIE 6337, 633702(2006).
    [CrossRef]
  5. M. Dyble, N. Narendran, A. Bierman, and T. Klein, “Impact of dimming white LEDs: chromaticity shifts due to different dimming methods,” Proc. SPIE 5941, 59411H (2005).
    [CrossRef]

2006 (2)

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

K. Man and I. Ashdown, “Accurate colorimetric feedback for RGB LED clusters,” Proc. SPIE 6337, 633702(2006).
[CrossRef]

2005 (2)

M. Dyble, N. Narendran, A. Bierman, and T. Klein, “Impact of dimming white LEDs: chromaticity shifts due to different dimming methods,” Proc. SPIE 5941, 59411H (2005).
[CrossRef]

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, 054506 (2005).
[CrossRef]

2004 (1)

Y. Ohno, “Color rendering and luminous efficacy of white LED spectra,” Proc. SPIE 5530, 88–98 (2004).
[CrossRef]

Ashdown, I.

K. Man and I. Ashdown, “Accurate colorimetric feedback for RGB LED clusters,” Proc. SPIE 6337, 633702(2006).
[CrossRef]

Bierman, A.

M. Dyble, N. Narendran, A. Bierman, and T. Klein, “Impact of dimming white LEDs: chromaticity shifts due to different dimming methods,” Proc. SPIE 5941, 59411H (2005).
[CrossRef]

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, 054506 (2005).
[CrossRef]

Dyble, M.

M. Dyble, N. Narendran, A. Bierman, and T. Klein, “Impact of dimming white LEDs: chromaticity shifts due to different dimming methods,” Proc. SPIE 5941, 59411H (2005).
[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, 054506 (2005).
[CrossRef]

Klein, T.

M. Dyble, N. Narendran, A. Bierman, and T. Klein, “Impact of dimming white LEDs: chromaticity shifts due to different dimming methods,” Proc. SPIE 5941, 59411H (2005).
[CrossRef]

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, 054506 (2005).
[CrossRef]

Man, K.

K. Man and I. Ashdown, “Accurate colorimetric feedback for RGB LED clusters,” Proc. SPIE 6337, 633702(2006).
[CrossRef]

Narendran, N.

M. Dyble, N. Narendran, A. Bierman, and T. Klein, “Impact of dimming white LEDs: chromaticity shifts due to different dimming methods,” Proc. SPIE 5941, 59411H (2005).
[CrossRef]

Ohno, Y.

Y. Ohno, “Color rendering and luminous efficacy of white LED spectra,” Proc. SPIE 5530, 88–98 (2004).
[CrossRef]

Salsbury, M.

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

Schubert, E. F.

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, 054506 (2005).
[CrossRef]

Speier, I.

I. Speier and M. Salsbury, “Color temperature tunable white light LED system,” Proc. SPIE 6337, 63371F (2006).
[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, 054506 (2005).
[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, 054506 (2005).
[CrossRef]

Proc. SPIE (4)

K. Man and I. Ashdown, “Accurate colorimetric feedback for RGB LED clusters,” Proc. SPIE 6337, 633702(2006).
[CrossRef]

M. Dyble, N. Narendran, A. Bierman, and T. Klein, “Impact of dimming white LEDs: chromaticity shifts due to different dimming methods,” Proc. SPIE 5941, 59411H (2005).
[CrossRef]

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

Y. Ohno, “Color rendering and luminous efficacy of white LED spectra,” Proc. SPIE 5530, 88–98 (2004).
[CrossRef]

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Figures (11)

Fig. 1
Fig. 1

LED model S LED ( λ ) with λ o = 629.2 nm compared with the SPD of a typical real red LED.

Fig. 2
Fig. 2

Curve of λ o versus I F for a typical real red LED.

Fig. 3
Fig. 3

Curve of Δ λ o versus I F for a typical real red LED.

Fig. 4
Fig. 4

Relative SPDs of the model and real red LEDs at different drive currents: (a) the model red LED and (b) the real red LED.

Fig. 5
Fig. 5

S W ( λ ) , S B ( λ ) , and S F ( λ ) of a typical real p-W LED.

Fig. 6
Fig. 6

Relative SPDs of the model and real p-W LEDs at different drive currents: (a) the model p-W LED and (b) the real p-W LED.

Fig. 7
Fig. 7

Curve of I F versus Φ for a typical real p-W LED.

Fig. 8
Fig. 8

Curve of P in versus Φ for a typical real p-W LED.

Fig. 9
Fig. 9

Relative SPDs of WW, red, green, and blue LEDs.

Fig. 10
Fig. 10

Relative SPDs of CW, red, amber, and green LEDs.

Fig. 11
Fig. 11

Relative SPDs of NW, red, green, and blue LEDs.

Tables (8)

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Table 1 Values of Parameters of the Red LED at Different Drive Currents

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Table 2 Chi 2 / DoF for the Model and Real SPDs of the Red LED at Different Drive Currents

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Table 3 Values d u v of the Model and Real Red LEDs

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Table 4 Chi 2 / DoF for the Model and Real SPDs of the p-W LED

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Table 5 Values d u v of the Model and Real p-W LEDs at Different Drive Currents

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Table 6 Predicted and Measured Results of the WW/R/G/B Cluster

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Table 7 Predicted and Measured Results of the CW/R/A/G Cluster

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Table 8 Predicted and Measured Results of the NW/R/G/B Cluster

Equations (10)

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

S LED ( λ , λ o , Δ λ ) = [ g ( λ , λ o , Δ λ ) + k 1 g ( λ , λ o , Δ λ ) k 2 ] / ( 1 + k 2 ) ,
Δ λ = { Δ λ 1 ,     ( λ < λ o ) Δ λ 2 ,     ( λ λ o ) ,
k i = { k i 1 ,     ( λ < λ o ) k i 2 ,     ( λ λ o ) ,
λ o ( I F ) = A λ o exp ( B λ o I F ) + C λ o ,
Δ λ i ( I F ) = A Δ λ i + B Δ λ i I F ,
k i ( I F ) = A i exp ( B i I F ) + C i ,
S W ( λ ) = S B ( λ ) + S F ( λ ) ,
S F ( λ , I F ) = S F ( λ , I F max ) + A F exp ( B F I F ) ,
I F ( Φ ) = k I Φ γ ( 1 + c I Φ 2 ) ,
P in ( Φ ) = k P Φ γ ( 1 + c P Φ 2 ) ,

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