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Transformations in Lighting2011 DOE Solid-State Lighting R&D Workshop

pg. 1Copyright 2011, Cree, Inc. R.C. Tuttle

White LED Chromaticity Control-The State of the Art

Ralph C. Tuttle

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1. Chromaticity Requirements

2. Meeting the Requirements

Outline:

pg. 2Copyright 2011, Cree, Inc. R.C. Tuttle

3. Effects of Operating Conditions on Color Point

4. Long Term Chromaticity Control

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ANSI_NEMA_ANSLG C78.377-2008

Chromaticity Requirements for Energy Star Products

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ANSI_NEMA_ANSLG C78.377-2008

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ANSI_NEMA_ANSLG C78.377-2008

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ANSI_NEMA_ANSLG C78.377-2008

(.2409, .5251)

pg. 6Copyright 2011, Cree, Inc. R.C. Tuttle

(.2339, .4994)

uv = .0266

A one step MacAdam Ellipse = .001

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NEMA Standards Publication SSL 3-2010

High-Power White LED Binning for General Illumination

pg. 7Copyright 2011, Cree, Inc. R.C. Tuttle

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Cree Standard Chromaticity Regions

Meeting C78.377 Requirements

pg. 8Copyright 2011, Cree, Inc. R.C. Tuttle

* Tested at 350mA, 25

C, 25ms

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Cree Easy White Chromaticity Regions

Meeting C78.377 Requirements

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Effects of Operating Conditions on Color

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Effects of Operating Conditions on Color

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XP-E shift in color point (u,v) vs Junction Temperature

10C

Effects of Operating Conditions on Color

pg. 12Copyright 2011, Cree, Inc. R.C. Tuttle

85C25C

When Tj increases from 25Cto 85C, the color point shifts.002 in the uv color space.

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50mA350mA

Cree XR-E LED Drive Current

Effects of Operating Conditions on Color

pg. 13Copyright 2011, Cree, Inc. R.C. Tuttle

1000 mA

When If increases from 350mA to

1000mA, color point shifts .002 inthe uv color space.

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350mA

Increase in If to 1000mA

Effects of Operating Conditions on Color

Commercially available LED for General Lighting

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Effects of Operating Conditions on Color

Temp Increases 25C to 85C

Chromaticity Shift Duv = +.006

Increase in Luminous Flux = +5%

pg. 15Copyright 2011, Cree, Inc. R.C. Tuttle

Relative Hot Lumens increasewith color shift due to eyeresponse.

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Long Term Chromaticity Control

pg. 16Copyright 2011, Cree, Inc. R.C. Tuttle

XPE XLamp

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Long Term Chromaticity Control

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Long Term Chromaticity Control LM-80 Testing

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1. LED manufacturers can provide very tight color bins for whiteLEDs that allow the user to effectively color mix to achieve verytight color point consistency.

2. LED manufacturers can provide very tight color bins (2-stepMacadam Ellipse) in some products.

3. Issues like droop and hot/cold factor can be greatly affected

In Summary

pg. 19Copyright 2011, Cree, Inc. R.C. Tuttle

by changes in chromaticity!4. Ask your LED supplier for data that shows the color point

behavior of LEDs under varying operating conditions.

5. Ask your LED supplier for data that shows the color pointstability over time (LM-80 test data).

6. If a supplier cant provide the data reconsider using that LED!

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Thank You!

Ralph C. Tuttle

pg. 20Copyright 2011, Cree, Inc. R.C. Tuttle

Cree, Inc.ralph_tuttle@cree.com

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pg. 21Copyright 2011, Cree, Inc. R.C. Tuttle