Why do my LED products of the same color temperature not look the same?

Introduction:

Color consistency plays a pivotal role in the world of LED lighting, ensuring that the visual experience remains uniform and pleasing to the eye. In this article, we will explore the nuances of color consistency, the metrics used to measure it, and how issues can manifest in LED lighting.

Color Differences and Measurement Metrics:

Color differences in LED lighting are typically characterized along two axes: blue/yellow and green/magenta. The blue/yellow difference is quantified through color temperature (in degrees Kelvin), while the green/magenta variation is described using a metric known as Duv.

• For color temperature, acceptable variation depends on the application, with +/-75K for warm white and +/-150K for normal or cool white generally considered noticeable.

• Duv, indicating green or magenta color shifts, is noticeable when differing by more than 0.002.

Sophisticated manufacturers use Standard Deviation Color Matching (SDCM) or MacAdam ellipses to express color consistency. This metric, measured in "steps," provides a comprehensive view of color variation, capturing both blue/yellow and green/magenta directions in a single number.

The Importance of SDCM: SDCM is superior to individual metrics like color temperature and Duv, as it accounts for variations in both directions and adjusts for differences at various color temperatures. A 5-step SDCM range is acceptable for standard applications, while more demanding uses, such as professional or architectural settings, may require a 3-step range.

Color Consistency Issues and Their Manifestations:

Color consistency issues in LED lighting typically fall into two categories:

1. Color Mismatch within a Single LED Strip Reel or Segment:

   • Occurs when individual LEDs on a strip exhibit noticeable color variations.
   • Caused by insufficient tolerance specifications during manufacturing.

2. Color Mismatch between LED Strip Reels or Segments:

   • Arises due to variations between batches or manufacturers.
   • Caused by differences in chromaticity bin selection or color measurement equipment calibration.
     

Addressing Color Shift Over Time:

LEDs may undergo color shifts over time due to degradation in phosphor or packaging materials. Consider the following factors:

• LEDs from the same batch and manufacturer typically shift at similar rates and directions.
• Adding or replacing LED lights, even from the same batch, after prolonged use may result in color differences.
• Visual matches today do not guarantee identical color changes over time, leading to potential color mismatch issues in the future.

Conclusion:

Understanding color consistency is crucial for ensuring a visually harmonious and consistent lighting experience with LED products. By considering metrics like SDCM and being mindful of issues that can arise within and between batches, manufacturers and end users can make informed decisions to achieve the desired visual impact and maintain consistency over time.