How to Read Spectral Charts

Dear friends,

When analyzing spectral charts, it’s important not to solely focus on color temperature and color rendering index (CRI). While CRI is commonly referenced, it isn’t the most valuable metric for assessing LED quality. The crucial metric to consider is the “color tolerance” value.

Understanding Color Tolerance

Color tolerance involves complex calculations that measure the color difference before and after installation. This difference arises from variations in chips and encapsulation processes, leading to batch-to-batch color differences in LEDs. Effective sorting can help achieve the desired color temperature range.

Figure 1 demonstrates that a smaller SDCM (Standard Deviation Color Matching) value indicates finer sorting. Although this results in lower yield, it ensures better color temperature consistency. Generally, an SDCM value of less than 3 signifies high-quality light strips.

Figure 2 shows that a smaller DUV (Delta UV) value indicates more accurate color representation. Larger DUV values can result in greenish or yellowish tints. For optimal quality, select light strips with a DUV value of less than 0.001.

Practical Implications

With identical chips and encapsulation processes, LEDs with smaller color tolerance are more expensive. The yield for 5-step color tolerance is around 90%, while for 3-step, it drops to about 70%, increasing costs by roughly 30%. A noticeable color temperature difference is approximately 200K.

However, when sorting finer than 3-step, single LED differences become apparent. In high-density strips (200+ LEDs per meter), mixed light reduces these visible differences. Even with 5-step sorting, the final product usually doesn’t exhibit noticeable color temperature discrepancies.

These insights are based on my colleague’s five years of practical experience in the industry. If there are any inaccuracies, please advise. The industry often features low quality and high prices, making it challenging for consumers to discern the best products. Over time, however, the truth about quality will become evident.

Feel free to share your thoughts and experiences in the comments below.

This blog post is inspired by practical industry insights to help consumers make informed decisions about LED products.

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