EMRP-ENG62: Metrology for efficient and safe innovative lighting

• Forschungsstelle: METAS
• Projektnummer: F-5116.30039
• Projekttitel Englisch: EMRP-ENG62: Metrology for efficient and safe innovative lighting

Schlüsselwörter (Englisch)

SSL efficacy, dimming, SSL standard, flickering index, OLED, SSL aging, SSL reliability, SSL life time, safety, perception

Kurzbeschreibung (Englisch)

The lighting industry has experienced a revolution with the arrival of novel lighting technologies in particular Solid state Lighting (SSL), which comprises both non-organic semiconductor-based Light Emitting Diodes (LEDs) and organic LEDs (OLEDs). SSL has clear advantages in energy efficiency over conventional lighting technologies, and since 19 % of electricity worldwide is used for lighting, this can contribute significantly to saving energy problems worldwide and contributing to Europe’s 2020 strategy.
In order to validate performance claims and stimulate user confidence, as well as facilitate efficient development of SSL products, dedicated metrology is needed. Conventional optical metrology was based on incandescent light sources. During a joint research project (JRP) in the frame of the EMRP 2009 Energy Call, basic metrology for first-generation SSL products was developed. Now, a new generation of SSL products, based on novel technologies (notably OLEDs and OLED arrays, nano-structured and phosphor-free LEDs, and high-power LED structures), is appearing. The research in metrology needs to keep pace with these technical developments and dedicated traceable measurement solutions are needed to sustain the innovation and user uptake of novel SSL products.
A second area where metrology is urgently needed is in the area of lifetime estimation. Lifetime predictions reach in the tens of thousands of hours. This forms a major benefit and underpins the economic viability of SSL products, which require higher initial investment, but methods to assess the reliability of these claims are lacking.
In this JRP, a consortium of national metrology institutes (NMIs) from ten European countries work together, in close collaboration with industry and academia, to establish traceability for new generation SSL and SSL lifetime, taking into account important aspects as safety and human comfort.

This project is part of the European Metrology Research Programme (EMRP, http://www.euramet.org/index.php?id=emrp); it is partly funded by the European Union on the basis of Decision No 912/2009/EC.

Projektziele (Englisch)

The specific objectives of this JRP are:

1. To develop sets of optical and electrical reference standards to calibrate as well as to characterise the setups used in test laboratories and to verify their capability to perform particular measurements of novel SSL (WP1);
2. To study the feasibility of using standard measurement equipment for 3D complex goniometric measurements of large area and/or complex “next generation” SSL (WP2);
3. To develop methods for reliable electrical power measurements of AC-operated mature SSLs with the focus on developing an impedance stabilisation network; develop methods for electrical and optical measurements of pulsed SSL (WP2);
4. To improve measurement methods and decrease uncertainty in photometrical parameters of OLED measurements (WP2);
5. To deliver a full set of metrics that are currently lacking in metrology for safety and comfort aspects through the development of instrumentation and measurement methods and through performing studies on (a) flicker/stroboscopic effect; (b) blue hazard; (c) well-being/comfort experience; (d) lighting quality perception (WP3);
6. To develop measurement methods and establish traceability for lifetime and reliability testing of SSL products and disseminate these to international standardisation bodies; Investigate various ageing mechanisms involved in material degradation of novel SSL devices (WP4).
7. To spread the use of the developed transfer standards for test laboratories worldwide by establishment of a Technical Committee in CIE for the publication of an international CIE recommendation based on the work of WP1 (WP5).

Abstract (Englisch)

One of the main objectives of this project was the development of a new SSL based (solid state lighting) transfer standards (MTS) that can be used to calibrate and characterize goniophotometers and integrating spheres. This was successfully realized. For this purpose, some strategies for the measurement possibilities with such an MTS were investigated.

Furthermore, in the course of the project, so-called add-ons were developed for the MTS, which simulate a simulation of flat illuminated areas, round radiators and fluorescent tubes. These add-ons can be mounted on the MTS and used for the respective measurements and characterizations.

Another milestone of the project was the development of an impedance stabilization network (ISN) for the reliable measurement of the electrical parameters of SSL products. By analyzing the measurement results of the existing measurement setups of the various project partners, a schema of a network was developed. Based on this scheme, the hardware was then set up and successfully tested in a measurement comparison. With some SSL lamps it could be shown that the electrical values measured by the individual project partners had a better comparability with the help of this ISN than without ISN.

Finally, the knowledge gained during the CIE Tutorial in May 2017 was passed on to the potential users (ie calibration and testing laboratories)

Umsetzung und Anwendungen (Englisch)

During the stakeholder meetings, the multiple transfer standard (MTS) met with great interest from device manufacturers and test laboratories. A prominent manufacturer is interested in advancing the development of the MTS and possibly distributing it.

Due to the only partially successful measurements of the electrical parameters of the SSL products with the ISN, there is a need for further development, which could possibly be promoted within the scope of a new joint research project.

Publikationen / Ergebnisse (Englisch)

U. Krüger, P. Blattner, R. Horni-scher, W. Bechter, W. Steudtner, W. Jordan, Measurement uncertainty of photometric measurements considering the requirements of the new international standard CIE S 025 / E:2015 "Test Method for LED Lamps, LED Luminaires and LED Modules, Proceedings of the 28th Session of the CIE, Manchester, United Kingdom, 28 June – 4 July 2015.