NIST Role in Supporting Solid State Lighting Initiative

Transcription

1 CORM 2007 Annual Meeting, Gaithersburg, May 8-11, 2007 NIST Role in Supporting Solid State Lighting Initiative Yoshi Ohno, Ph.D. Optical Technology Division National Institute of Standards and Technology Gaithersburg, Maryland

2 Outline 1. NIST Calibration Services for LED/SSL devices 2. NIST Supports Standardization for SSL 3. NIST Supports DOE on Commercialization Support of SSL 4. Research on Color Quality of LED/SSL sources

3 1. NIST Calibration Facilities and Services for LEDs and SSL Products Photometric and radiometric quantities Total luminous flux (lm) Total radiant flux (W) ( nm) Luminous efficacy (lm/w) Luminous Intensity CIE Averaged LED Intensity A/B Luminous intensity distribution (small sources) Color quantities Chromaticity coordinates (x,y), (u, v ) Correlated color temperature Color Rendering Index (CRI R a ) Dominant wavelength λ d Spectral distribution (total spectral radiant flux)

4 Calibration Facilities 2.5 m integrating sphere Optical Technology Division Total luminous flux (lm) Total radiant flux (W) ~350 nm to 830 nm Spectral distribution Chromaticity, CCT, CRI (4 π integrated) 25 C ambient temp. Individual LEDs SSL products up to ~30 cm diameter or linear ~1.5 m long. 4

5 Absolute Integrating Sphere Method applied spectral Used for color and radiant flux calibration External reference flu " #,ref (#) = A $ E # (# Spectral radiant flux test lamp: " #,test (#) = y test (#) y ref (#) $ k cor(#) k corr (λ): correction fa Absolute scale of radiant flux is based on the NIST lumen.

6 1.25 m Gonio-spectroradiometer (developed for total spectral radiant flux scale) Servo motor Stepping motor! Light trap Encoder Servo motor Spectroradiometer " Laser Rotation coupling Irradiance head Fiber bundle Total spectral radiant flux (W/nm) Luminous intensity distribution Color uniformity ~25 C room temp. Radius 1.25 m. Limited to produ smaller than 20 cm diam.

7 Data example Luminous intensity distribution Color uniformity [cd]

8 Photometric bench 4 m long Luminous int (cd) Averaged LE intensity (A & Illuminance ( Luminance (c ~25 C ambie

9 Other NIST instruments for LEDs Goniophotometer for luminous intensity distribution Reference spectroradiometer (double-monochromator) for LED color measurement Variable temperature chamber (~10 C to 35 C) Optical Technology Division 9

10 Facility to be utilized for SSL measurements Retroreflection Measurement Facility (CHARM) 35 m dark room tunnel 6-axis high-precision goniometer Basically for measurement of flat surface samples. Plan to add modification to measure large or narrow beam SSL products

11 2. NIST Supports Standardization for SSL NIST is playing active role in standardization for measurements of SSL products, working with ANSI, IESNA, NEMA, and CIE, and in support of DOE. NIST takes leadership in developing ANSI C78.377A Specifications for the Chromaticity of SSL products (CDC2) IESNA LM-79 Approved Method for Electrical and Photometric Measurement of SSL Products (CDC2) CIE 127:2007 Measurement of LED (just published) CIE TC1-69 Color Rendition of White Light Sources (W. Davis)

12 ANSI C78.377A Specifications for the Chromaticity of SSL products (Draft) Table 1. Nominal CCT 1) Target CCT and tolerance (K) Target Duv and tolerance 2700 K 2725 ± ± K 3045 ± ± K 3465 ± ± K 3985 ± ± K 4503 ± ± K 5028 ± ± K 5665 ± ± K 6530 ± ± Flexible CCT ( K) T 2) ± T 3) D uv 4) ± ) Six of the nominal CCTs correspond to those in the fluorescent lamp specification [2]: 2700 K, 3000 K (Warm White), 3500 K (White), 4100 K (Cool White), 5000 K, and 6500 K (Dayligh respectively.

13 ANSI C78.377A Specifications for the Chromaticity of SSL products (Draft)

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15 Flexible Color 2) T is chosen to be at 100 K steps (2800, 2900,., 6400 K), excluding those eight nominal CCTs listed in Table 1. 3) T is given by "T = # T # T ) D uv is given by D uv = 57700# (1/T ) 2 $ 44.6 # (1/ T )

16 IESNA LM-79 Approved Method for Electrical and Photometric Measurement of SSL Products (Draft) Covers SSL products complete with electronics and heat sinks in one unit. Does not cover LED modules, LED packages, nor individual LEDs. Addresses both aspects of lamp photometry and luminaire testing (SSL products are not separated into lamp and fixture) Covers measurements of Total luminous flux (lumen) Luminous efficacy (lm/w) Chromaticity, CCT, CRI (4 π integrated)? Intensity distribution (currently not covered)

17 IESNA LM-79 Approved method for electric and photometric measurement of SSL products (Draft) " Total spectra% $ ' # radiant flux & Recommends use of a spectroradiometer with a sphere. No spectral mismatch errors for luminous flux. Chromaticity and luminous flux can be measured at the same time. Total spectral radiant flux standards now available from NIST.

18 CIE 127:2007 Measurement of LED (2nd ed. Major changes from last version (1997) New section on total luminous flux measurement. - New sphere geometries recommended - Partial LED flux defined. New section on spectral measurement (for colorimetric as well as photometric quantities) - Input geometries (irradiance mode, total flux mode, partial flux mode) - New recommendation on bandwidth and scanning interval (5 nm, for color) " LED,x 50 mm diam. d x

19 A big issue in SSL Large gap between published LED chip performance (lm/w) and SSL products performance (lm/w). LED specifications given for T j =25 C (pulse measurement) LEDs in SSL products are operating at much higher temperature. Drop of lm/w is typically 1/2 to 1/3. A standard for high power LED specifications for more realistic conditions as used in luminaires is badly needed. (Example)

20 CIE TC1-69 Color Rendition by White Light Sources Established in May Chair: Wendy Davis (NIST) TR: Investigate new methods for assessing the colour rendition properties of white-light sources used for illumination, including solid-state light sources, with th goal of recommending new assessment procedures. Color Quality Scale (developed by NIST) has been proposed and to be discussed. Workshop on Color Rendering at CIE Beijing Session (July 2007) chaired by Y. Ohno

21 3. NIST Supports DOE on Commercialization Support of SSL NIST is funded by DOE for Developing NVLAP program. required for Energy Star. Standards development Supporting product testing

22 DOE Energy Star program for SSL products SSL products for general illumination only Residential and commercial applications Designed to ensure energy efficiency (also quality) relative to existing sources Two categories - Category A and B Requirements for luminaire efficacy, chromaticity, and CRI (>75 for indoor applications) Requires measurements by accredited laboratories. Under cabinet kitchen Portable desk/task Recessed downlights Outdoor porch lights Outdoor step lights Outdoor pathway lights Category B Min. lm nd draft 4/9/

23 DOE SSL Commercial Product Testing Program (CPTP) Workshop held Oct. 27, Objective: - Provide high quality performance information, discourage low quality products. - Support R & D planning - Support ENERGY STAR - Inform industry test procedures and standards Key actors: - DOE, PNNL - Independent testing labs Tests may include total luminous flux, luminous Efficacy, color characteristics stability, life testing, and more.

24 Tests in accordance with LM-79. NIST supports to verify measurements by independent testing labs. NIST 2.5 m sphere measuring SSL products Optical Technology Division 2

25 Developing NVLAP program for SSL products NIST OTD working with NIST NVLAP to establish a NVLAP Testing Program for Energy Efficient SSL Products. (Handbook 150-A being developed) IESNA LM-79 as the main reference for test procedures NIST OTD is to develop protocols and transfer standards used for round robin and proficiency testing, and perform these tests.

26 4. Research on Color Quality of SSL sources Vision Science Project at NIST Develop new CIE standard for color rendering of light sourc CRI CQS Develop state-of-the-art Color Vision Experiment Facility using spectrally tunable lighting sources. Research on other fundamental color-related questions in lighting.

27 Thank you for your attention. Questions? Contact: