Full Content is available to subscribers

Subscribe/Learn More  >
Proceedings Article

Characterizing white LEDs for general illumination applications

[+] Author Affiliations
Nadarajah Narendran, Nishantha Maliyagoda, Andrew Bierman, Richard M. Pysar, Martin Overington

Rensselaer Polytechnic Institute (USA)

Proc. SPIE 3938, Light-Emitting Diodes: Research, Manufacturing, and Applications IV, 240 (April 17, 2000); doi:10.1117/12.382836
Text Size: A A A
From Conference Volume 3938

  • Light-Emitting Diodes: Research, Manufacturing, and Applications IV
  • H. Walter Yao; Ian T. Ferguson; E. F. Schubert
  • San Jose, CA | January 20, 2000

abstract

During the past few years several manufacturers have introduced white Light Emitting Diodes (LEDs). At the present time these LEDs do not provide sufficient luminous flux for general lighting applications. Many manufacturers are studying the possibility of grouping several LEDs and overdriving them to produce more luminous flux. The impact of higher drive current on long-term performance of LEDs is not well known within the lighting community. Therefore, an experimental study was conducted to investigate the photometric characteristics of white LEDs as a function of time for different drive currents. The LEDs investigated in this study were the 5-millimeter type that uses GaN-based blue LEDs and Y3Al5O12 (yttrium aluminum garnet) phosphors (YAG phosphors). These LEDs produced 65 percent more light output at 55 mA compared to the light output at 20 mA. Groups of ten LEDs were driven continuously at constant current 20, 30, 50, 70, 90, and 110 mA and their relative light output were monitored at regular intervals for over 4000 hours. The light output degradation rate increased with increasing drive currents. Typically, LED manufacturers do not recommend driving these LEDs above 20 mA. However, it was noticed that the light output of these LEDs degraded to 65% of its initial value around 4000 hours even for those LEDs driven at 20 mA, which is the manufacturer recommended value for drive current. Considering the amount of flux produced by these 5 mm type white LEDs and their light output degradation rate, they are not yet suitable for general lighting applications.

© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Citation

Nadarajah Narendran ; Nishantha Maliyagoda ; Andrew Bierman ; Richard M. Pysar and Martin Overington
"Characterizing white LEDs for general illumination applications", Proc. SPIE 3938, Light-Emitting Diodes: Research, Manufacturing, and Applications IV, 240 (April 17, 2000); doi:10.1117/12.382836; http://dx.doi.org/10.1117/12.382836


Access This Proceeding
Sign in or Create a personal account to Buy this proceeding ($15 for members, $18 for non-members).

Figures

Tables

NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging & repositioning the boxes below.

Related Book Chapters

Topic Collections

Advertisement
  • Don't have an account?
  • Subscribe to the SPIE Digital Library
  • Create a FREE account to sign up for Digital Library content alerts and gain access to institutional subscriptions remotely.
Access This Proceeding
Sign in or Create a personal account to Buy this proceeding ($15 for members, $18 for non-members).
Access This Proceeding
Sign in or Create a personal account to Buy this article ($15 for members, $18 for non-members).
Access This Chapter

Access to SPIE eBooks is limited to subscribing institutions and is not available as part of a personal subscription. Print or electronic versions of individual SPIE books may be purchased via SPIE.org.