What is the criterion for LED failure? What about the failure rate?
Similar to other electronic components, the failure of LED refers to: within a specified time, the device cannot complete the specified function, which is called failure of the device. The so-called loss of function is called failure.
For the LED, the change of one or several parameters can be used as the criterion for failure. For example, the ratio of LED luminous intensity to initial value is often used as the criterion, which is defined as: with the increase of LED working time, when the luminous intensity Iv drops to a certain percentage of its initial value, the LED is considered to be invalid. This percentage can be 50% or 20% as a criterion.
Obviously, it is not meaningful to evaluate the failure level of a single LED. Usually, the failure evaluation is only practical for a group of objects with the same properties. This means that from a LED population, it is more meaningful to evaluate the percentage of the number of device failures in a certain period of time to the total population of the entire population, which is the so-called failure rate to evaluate the level of device failure.
The definition of failure rate refers to: the percentage of a certain type of object failure (loss of specified function) in unit time is represented by the symbol λ, and the unit is %.
For example: in a certain system, a total of 100,000 LEDs are used, and the number of failures per unit time is 1, then the failure rate of the LEDs in this system is 1 in 100,000.
