Understanding L & B Figures

When it comes to understanding the expected lifetime of LEDs, the terms “L” and “B” figures play a crucial role. Let’s break down what these figures mean:

  1.  L-value:
    • The “L” value, also known as lumen maintenance, represents the percentage of initial brightness (luminous flux) that an LED is expected to maintain over its operational life.
    • For example, if an LED is rated with an L70 value, it means that after a specified number of hours (usually denoted after L), the LED will still be emitting at least 70% of its original brightness.
    • Common values you might encounter include L70, L80, and L90, with higher values indicating better longevity and performance.
  2. B-value:
    • The “B” value represents the percentage of the LED population that is expected to fail before reaching the specified L-value.
    • For instance, if an LED is rated as “L70 B50,” it means that 50% of the LED population is expected to fail before they reach 70% of their initial brightness.
    • Different B-values indicate different reliability levels. For example:
      • B50: 50% of the LEDs are expected to fail before reaching the specified L-value.
      • B70: 70% of the LEDs are expected to fail before reaching the specified L-value.
      • B10: Only 10% of the LEDs are expected to fail before reaching the specified L-value.
    • The lower the B-value, the more reliable the LED is considered to be.

 

If you are still need some assistance with L & B figures, please do not hesitate to contact our design team who will be more than happy to assist you.