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Overview of measurement standards for solid state lighting

Yoshi OhnoDirector of CIE Division 2

Member of ANSI C78-09, IESNA TPCOptical Technology Division

National Institute of Standards and TechnologyGaithersburg, Maryland USA

CORM 2009 NIST Tutorial Workshop, Gaithersburg, MD, May 5, 2009

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Solid State Lighting is becoming a reality

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Current State of White LEDs

From presentation by Fred Welsh at 2009 DOE SSL Program Planning Workshop, Feb. 2009, San Francisco.

Luminous Efficacy Goal

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Problems/Concerns in the industry

• Some very low quality products in the market (dim, short life, bad color).

• Inaccurate performance claims • Insufficient information on product labels• Many questions on color quality (rendering)• Lighting designers still do not trust SSL products. They say

more standards are needed.• Still high cost (but government incentives to use SSL products

are high.)

* US DOE is addressing these problems with the Energy Star, CALiPER and other programs.

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DOE’s Solid State Lighting Program Strategy

From presentation by James Brodrick, DOE Energy Star Workshop, May 15, 2008

CALiPER

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http://www1.eere.energy.gov/buildings/ssl/benchmark.html

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http://www1.eere.energy.gov/buildings/ssl/advocates.html

SSL Quality Advocates• Program jointly developed

by DOE and NGLIA • a voluntary pledge program

to assure that LED lighting, as it reaches the market, is represented accurately.

• introduces the Lighting Facts label, similar to the FDA Nutrition Facts label.

• provides a quick and simple summary of product performance data as measured by the new industry standard for testing photometric performance, IESNA LM-79-2008.

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1. Under-cabinet kitchen lights

2. Under-cabinet shelf-mounted task lights

3. Portable desk/task lights

5. Out-door wall-mounted portch

6. Out-door step lights

7. Out-door pathway

DOE SSL Energy Star (Category A)

4. Recessed down lights

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SSL Energy Star Specifications

Required standards for

• Test method and measurement …….…….… IESNA LM-79

• Chromaticity specification ……………………. ANSI C78.377

• Test method for lifetime of LEDs …..…….…. IESNA LM-80

• Laboratory accreditation for measurement .. NVLAP EELP-SSL

• Terminology …………... ANSI/IESNA RP-16 addendum a

Program started from Sep. 30, 2008.

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Addendum to ANSI/IESNA RP-16-05Published in May 2008

6.8 Light Emitting Diode6.8.1 LED die6.8.2 LED Bin6.8.3 Power source6.8.3.1 Power supply6.8.4 LED control circuitry6.8.4.1 LED driver6.8.4.2 LED driver, Class II6.8.5 LED luminaire6.8.5.1 LED package6.8.5.2 LED array6.8.5.3 LED module6.8.5.4 LED lamp, non-integrated6.8.5.5 LED lamp, integrated

Addendum a to ANSI/IESNA RP-16-05(under continuous maintenance)

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Addendum a to ANSI/IESNA RP-16-05

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Revision of this Addendum is being discussed at IESNA TPC.

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Published, May 2008

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Covers LED luminaires and integrated LED lamps.

Covers measurements of• Total luminous flux (lumen)• Luminous efficacy (lm/W)• Chromaticity, CCT, CRI (4 π integrated)• Angular intensity distributions

Methods using• Sphere-spectroradiometer• Sphere-photometer• Goniophotometer

IESNA LM-79 Approved Method for Electrical and Photometric Measurement of SSL Products

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ANSI C78.377 Specifications for the Chromaticity of SSL products

Published Feb. 2008

• For indoor applications only

• No standards for outdoor applications

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Published, Oct. 2008

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Scope…. This document provides the methods of the measurement of lumen maintenance of sources including LED packages, arrays and modules only. … This approved method does not provide guidance or make any recommendation regarding predictive estimations or extrapolation.

IES LM-80-08 Approved Method for Measuring Lumen Maintenance of LED Light Sources

IES TM-21-xx

Testing at the LED case temperatures55°C, 85°C, and a 3rd temperature selected by manufacturer, for 0 to 6000 h or longer. Ambient temperature within -5°C from the case temperature.

Model 0Model 1Model 2Model 3Model 4Model 5Model 6Model 7Data

Lumen Maintenance Life:L70 (hours): 70% lumen maintenanceL50 (hours): 50% lumen maintenance

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LED arrays / modules

LED luminaires

LED packages(low power) (high power) Integrated LED lamps

LED light engines

Many Standards needed for LED/SSL

Complete SSL products

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LED chips/ packages(low power) (high power) SSL products

(Integrated LED lamps & LED luminaires)

LED light engines

IES LM-79 Photometric meas.

ANSI C78.377 Chromaticity

CIE 127:2007

Definitions (terminology) IES RP-16 addendum a

Safety

IES LM-80 Lumen maintenance

Current Status of Standardization Activities

LED arrays / modules

(ASSIST Recommends ..)

CIE TC2-63, 64

CIE TC2-50 LED clusters and arrays

CIE TC2-46

CIE TC1-69 Color rendering

IEC xx (performance of self-ballasted LED lamps)

UL 8750CIE TC2-58 radiance/luminanceSeveral projects in IEC TC34A

IESNA new project

IES TM-21IESNA new project

IEC TS 62504

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Large Gap between LED manufacturers and Lighting Industry

<LED manufacturer>

<Lighting industry>

• LEDs measured in production.

• LEDs are measured with short pulses.

• LEDs are binned and rated at Tj=25°C.

• LEDs in luminaires are hot (Tj= 60 °C to over 100°C)

• Photometric measurements in steady DC mode.

LED performance varies with temperature

Performance of LEDs = Performance of SSL products

Pulse vs.

DC ?

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High power LED: an LED device that requires a heat sink or other type of thermal management as an integral part of the operation.

Covers LED packages and LED arraysCovers measurements in pulse mode as well as DC mode (NIST method)

Covers measurements of• Total luminous flux (lumen)• Luminous efficacy (lm/W)• Chromaticity, CCT, CRI

Methods using• Sphere-spectroradiometer• Sphere-photometer• Goniophotometer

IESNA LM-xx Approved Method for Electrical and Photometric Measurement of High Power LEDs

Status: first draft

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Division 2 Physical Measurement of Light and Radiation(Director, Y. Ohno, USA) TC2-46 CIE/ISO standards on LED intensity measurements (J.

Scarangello, USA)TC2-50 Measurement of the optical properties of LED clusters and

arrays (J. Schuette, Germany)TC2-58 Measurement of LED radiance and luminance (K. Kohmoto,

Japan)TC2-63 Optical measurement of High-Power LEDs (Y. Zong, USA)TC2-64 High speed testing methods for LEDs (G. Heidel, Germany)

Division 1 Vision and Color (Director, R. Luo, UK) TC1-69 Colour Rendition by White Light Sources (W. Davis, USA)

Work in progress in CIE on LED/SSL

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Work in progress in IEC on LED/SSL

IEC 62031 – Safety standard for LED modules IEC 62560 – Safety standard for self-ballasted LED lamps IEC/PAS 62612 Performance standard for self-ballasted LED lampsIEC TS 62504 – Terms and definitions for LEDs and LED modules in general lightingIEC 62384 – Performance of control gear for LED modulesIEC 62471-2 – Photobiological safety; Guide

IEC TC34 Lamp and Related EquipmentSC34A Lamps and glow starters (MT PRESCO)SC34B Lamp caps and holdersSC34C Lamp control gearSC34D Luminaires

<Working documents>

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International Intercomparison of LED measurements Organized by APMP (Asia Pacific Metrology Program) – Regional metrology organization, connected to International Committee of Weights and Measures (CIPM), Consultative Committee of Photometry and Radiometry (CCPR)

Measurement quantities• Total luminous flux• CIE Averaged LED Intensity• Chromaticity (x, y)

15 Participants (National labs)KRISS, Korea (Pilot lab)CENAM, MexicoCMS-ITRI, TaiwanLNE, FranceMIKES, FinlandMETAS, SwitzerlandMKEH, HungaryNIST, USANMIJ, JapanNMi-VSL, NetherlandsNMIA, AustraliaNPL, UKPTB, GermanySPRING, SingaporeVNIIOFI, Russia

Artifacts: 5-mm LEDs, 20 mA

A set of 14 LEDs (red, green, blue, white)

Schedule:Measurements: July 2007 –Completion of report: Dec. 2009

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Thank you for your attention.

Contact: ohno@nist.gov