LM-80 is not equal to LED lamp / lamp life

I. Introduction

There are two important problems in the market of LED bulb:

The first is unclear. According to the testing industry LED Lighting Research Institute, more than 50% of the LED light bulb, the actual flux marked were lower than 10% of the nominal value of more than.

Second is uneven quality. Currently there is no set of specifications can be made clear the relationship between the price and quality of LED bulbs. Which consumers often take "apples and oranges" in comparison, some even spend a higher price, but did not get a relatively high quality of products, this kind of bad money drives out good situation more and more serious, also caused the attention of Europe and the United States and Japan LED lamps / bulbs identification and quality problems.

In view of this, the Ministry of Economic Affairs Bureau of energy for LED bulbs also accelerate the promotion of energy conservation standards, for this matter, the author is a joy, a worry. The joy is at least Taiwan is a common standard, can provide consumers to choose the LED bulb. Worry is that consumers spend a lot of money to buy in line with the "energy saving standard benchmark requirements of the project" LED bulbs, really have the quality of protection?

Two, lumen maintenance rate is sufficient to represent the LED lamp life?

Currently on the market more representative of the official specification, can be linked with the bulb life, should belong to the United States Environmental Protection Agency / energy star for LED bulbs / lamps issued by the LM-80 specification. However, since from this standard is issued, in North America has been the emergence of a number of different voices, some experts even began calling for reliability, should immediately stop using the LM-80 lumen maintenance (L70) as the LED lamp or lamp life is the only basis for judgment.

In fact, in 2006, the United States Department of energy solid state lighting (SSL) quality working group, invited 32 reliability experts, for LED reliability and life estimation methods for a very in-depth discussion. In consideration of the industrial capacity of LED then, the working group decided to lumen maintenance rate (L70) to represent the reliability of LED components and lamps will be the most significant, but also the most easily quantified indicators. The reason is that the traditional incandescent light bulbs in use, as long as the tungsten wire burned, said lamp life to, and LED light bulbs in the lumens of recession, is gradually slow, early in a recession, people in the vision is not the feeling, until the light source to the initial recession (L70) at 70%, people will feel light dimmed, then will affect the illumination. Therefore, the working group recommended that lumen maintenance rate (L70) as the sole basis for the LM-80 specification. But the point is that the lumen maintenance rate is not equal to the LED bulb or lamp life (Life Time), what are the problems with the LM-80 specification?

Three, apple to Apple: LED lamps are electronic products, not the traditional light bulb"

LED component life:

Basically, the LED element is a light emitting diode, which belongs to an electronic component. Therefore, if we want to talk about the life of LED components, we should use the mature electronic component accelerated life test (ALT) method, with the number of samples and statistical analysis of data, to assess the life of LED components. The current LM-80 specification, using three kinds of test temperature, with the energy star for lumen maintenance requirements, as the failure criteria of the LED element, in fact is not controversial, especially in the life of the TM-21 estimation approach after the release, more to solve the various manufacturers in the life of LED elements on each side of the the situation, but for lamp factory use LED elements, the possible point of contention is:

1 in the energy star in the /LM-80 specification, LED element must pass three different temperature test at each test temperature must be at least 20 LED element through the test of 6000 hours, and the lumen maintenance rate as the only basis to judge the success of the experiment. The dispute is that if in 6000 hours during the test, the LED components appear not bright or burned, can not be included in the lumen maintenance rate calculation, only the move has not meet the requirements of the life of LED component calculation.

2 if you want to do for the life calculation basis is feasible by using LM-80 test data, as long as the clear definition of those failure modes can represent the failure (e.g., lumen maintenance and dead burned, light, color coordinates / voltage / current offset), any failure of the definition of failure mode, which represents the life of the component to LED the. In addition to the grain quality, including the selection of packaging materials to the line, and so on, all affect the life and reliability of LED components. Therefore, for the implementation of LM-80 or life verification of LED components, the first through the "reliability qualification verification" is absolutely necessary.

Note: in the process of test execution LM-80/6000 hours, in order to reduce the LED failure and make the risk test interruption, usually LED will increase the number of components factory test sample, when the test process is part of LED lamp or early death, energy star is not included in the average fault samples allowed lumen maintenance calculation. But the request must be noted in the LM-80 report. Therefore, when reading the LM-80 report provided by the LED vendor, the lamp manufacturer should be more careful in addition to the test temperature and lumen maintenance rate.

LED lamp / lamp life

Is it true that the LED bulb or lamp life is really only a factor of lumen maintenance? Basically, the LED lamp is made up of a dimmer, a power supply, and a light emitting diode