" ... a light source that shifts in color too much over time is just as useless as one whose lumen output drops below an acceptable threshold.
"SSL’s capability for excellent color stability has already been demonstrated, so as the technology continues to develop, there should be no need to compromise in that area for other performance attributes."
James Brodrick
Lighting Program Manager, US Department of Energy
LD+A Magazine: Color Stability is Still a Question
"SSL’s capability for excellent color stability has already been demonstrated, so as the technology continues to develop, there should be no need to compromise in that area for other performance attributes."
James Brodrick
Lighting Program Manager, US Department of Energy
LD+A Magazine: Color Stability is Still a Question
Color Prediction & Control
QuarkStar is making fundamental breakthroughs in color shift prediction and stabilization (CSPS). By being able to predict color shift curves using just existing LM-80 data, QuarkStar offers solutions to control and compensate for these shifts without complicated and costly feedback systems. This means simple, elegant solutions guaranteeing color behavior for end customers, competitive advantages to chip and package manufacturers, and significant impacts on the high-profile high-value downstream market.
Focus Shifts From Lumens to Color
"... [QuarkStar's model] has the potential to change how the solid-state lighting (SSL) industry utilizes test and measurement guidance, and effectively end the notion that the lumen is the only light characteristic that matters with regard to LED lifetime performance."
Carrie Meadows
LEDs Magazine: Focus Shifts From Lumens to Color
Carrie Meadows
LEDs Magazine: Focus Shifts From Lumens to Color
An example of how color can shift
in four different LEDs over time |
The ProblemColor prediction - or, how to predict LED color shift behavior - and how to control it is a completely unsolved problem in LED lighting. It is considered one of the toughest problems in the field with no solution in sight ... until now.
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The SolutionQuarkStar has developed a completely new solution that can accurately predict LED color performance over long time intervals using just existing LM-80 data and our DCA algorithms. This means that control systems to compensate for color shift and provide color stability can be created without complicated feedback systems.
Being able to offer these solutions will provide new opportunities to guarantee color behavior to customers and competitive advantages to chip and package manufacturers, significantly impacting the high-profile and high-value downstream market. This ability to model and predict color stability behavior is already being incorporated into international industry standards. |
Predictions of color shifting LEDs using
QuarkStar's DCA algorithms with LM-80 data |
Presentations on QuarkStar's Color Prediction & Control Solutions
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Dr.2019 Strategies in Light
Chasing the Rainbow - Developing a Single Predictive Model for LED Metrics (recorded presentation coming soon) Presented by: Dr. Eric Bretschneider CTO QuarkStar Chair of the IES Solid-State Lighting Subcommittee |
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Predicting chromaticity shift in LEDs and SSL products
(originally aired November 27, 2018) Watch webcast (To skip registration, use this email: QS_color_shift_control@quarkstar.com) Lumen depreciation has been thoroughly studied in the solid-state lighting (SSL) world as the industry has sought to accurately predict the expected long lifetimes of LED-based products. But is a lighting product that significantly shifts in color or chromaticity over time still a viable product? Arguably, chromaticity shift can signal end of life just as easily as lumen depreciation in some applications. Industry experts have been investigating ways to quantify chromaticity shift for enhanced LED performance testing. This webcast will provide an overview of how the SSL design process can be enhanced by predicting chromaticity shift. Product developers and lighting specifiers will learn how such a data-driven method might be employed to help them choose products carefully and to confidently deploy SSL technology in color-critical applications. Presented by: Dr. Eric Bretschneider CTO QuarkStar Chair of the IES Solid-State Lighting Subcommittee |
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Models for Color Point Stability of LEDs:
(originally presented at 2017 Strategies in Light) Download presentation According to conventional wisdom the issue of projecting the color point stability of LED packages requires detailed knowledge of the construction materials and package architecture. This information along with extensive testing would allow development of an accurate model for predicting color point stability for the specific package from given manufacturer. Any change of the materials whether it be phosphors, encapsulants or packaging materials would require additional testing and a new model. Development of an industry standard method for projecting color point stability requires a model with minimal to no variables based on materials or supplier. As a result there is no currently accepted method for projecting color point stability. Recently a model called Differential Chromaticity has been developed to address these needs. The model was developed by evaluation of LED test sets that extend from 12,000 - 20,000 hours and includes multiple types of packages from multiple suppliers. To date the model has proven robust and is able to model multiple color shift mechanisms without adjustable parameters. Different types of color shift mechanisms will be discussed along with the principles of Differential Chromaticity. Utility of the model in predicting different color shift mechanisms will also be discussed. Presented by: Dr. Eric Bretschneider CTO QuarkStar |