What is color shift for a luminaire?

• For our discussion, “color shift” is what happens over TIME

• It does NOT mean initial variation in color from one luminaire to another or from one batch to another

Orange

Green

Blue

Pink

What are some of the causes for color shift in luminaires?

• Aging (for example, UV exposure may cause plastics to change color)

• Operating conditions (contaminants in the atmosphere may cause luminaire changes)

• Light engines may shift color over time (different engines shift color differently)

• Maintenance issues may cause the luminaires to look different over time (“wrong” parts installed)

Nearly all light engines havesome type of “color shift”

• Metal Halide lamps are notorious for color shift

• Incandescent bulbs color shift when dimmed

• Linear Fluorescents may not color shift “much” however, improper maintenance practices can cause obvious luminaire color shift over time

• LEDs use a technology that will shift color over time

Why does color shift with LED-based luminaires need attention?

• The causes of color shift with LEDs are not well understood or communicated

• Caliper testing shows color shift with LED-based luminaires is real and can be so great as to constitute a “failure” to an end user

• This creates a potential for trouble

Our group identified four challenges

• Describing color shift

• Projecting color shift

• Identifying design impact on color shift

• Testing for color shift

Describing color shift• How can we make description of color shift consumer “friendly”?

Too Hard Too Simple

Projecting color shift• Our group could not identify any team that is trying use that

data to project color shift over an extended period of time (50,000 or more hours)

Identifying designimpact on color shift

• Remember, the color shift in the final luminaire may be not be due to an LED color shift

• Examples include:– Different optics and designs age differently– Different environmental operating conditions may cause

different shifts over time– Different luminaire designs impact color– The luminaire may or may use active color

management

Testing for color shift

• Testing is not a one-size fits all situation

– LED-bulbs that replace A-lamps may be suited to one type of color shift testing

– Low-volume, decorative LED-based luminaires for lobbies and board rooms may need another type of testing

– Outdoor LED-luminaires may need different testing methods than ones in air-conditioned spaces

What did the group suggestthat we do next?

• Attack the issue by focusing on three segments:– Replacement lamps– Specification-grade luminaires– Standard-grade luminaires

• Try to get segment-specific working groups to organize and start work

Summary with respect to Color shift for LED-based luminaires:

• It is important

• It is complex

• It needs more work

• It can be segmented to facilitate action

• It may be up to us to keep it going

Thanks for your attention

• Terry ClarkCEO, Finelite, Inc.

tclark@finelite.com

• On behalf of the:– Solid-State Lighting Product Quality Initiative– Next Generation Lighting Industry Alliance with

the U.S. Department of Energy