Color Maintenance of LEDs in Laboratory and Field Applications

Royer, Michael P. ; Tuttle, Ralph ; Rosenfeld, Scott M. ; Miller, Naomi J.

Pacific Northwest National Laboratory (U.S.)

关键词: Light-Emitting Diode (Led), Color Shift, Color Stability, Color Maintenance, Warranty;   

DOI  :  10.2172/1096693
RP-ID  :  PNNL-22759
RP-ID  :  AC05-76RL01830
RP-ID  :  1096693

美国|英语

来源: UNT Digital Library

【 摘 要 】

Synopsis: To date, consideration for parametric failure of LED products has largely been focused on lumen maintenance. However, color shift is a cause of early failure for some products, and is especially important to consider in certain applications, like museums, where visual appearance is critical. Example data collected by the GATEWAY program for LED lamps installed in museums shows that many have changed color beyond a reasonable tolerance well before their rated lifetime was reached, necessitating replacement. Similar data collected by the CALiPER program between 2008 and 2010 reveals that many early products shifted beyond acceptable tolerances in as little as a few thousand hours. In contrast, data from the L Prize program illustrates that commercially available LED products can have exemplary color stability that is unmatched by traditional light sources. Beyond presenting data from the aforementioned DOE programs, this report discusses the metrics used for communicating color shift—namely MacAdam ellipses and Δu'v'—as well as providing guidance for end users on how to monitor color shift and what to look for in manufacturer warranties. Also included are descriptions of the physical changes that have been documented as leading to color shift in some example types of LED packages. As with complete products, the data presented herein for LED packages shows that a wide variety of products are available; in order for specifiers and consumers to make educated choices, more detailed and standardized information should be made available.