Lamps also have a life span.
Actually the lamps and lanterns is similar to our mankind, have the life, with the passage of time, the function mechanism of lamps and lanterns also can decrease ceaselessly.
Whether incandescents, fluorescent lamps, energy-saving lamps or LED lights can't avoid the "end of life", this is the lighting problem.
What is light decay?
At present our country has not made the definition and general standard of droop, but generally refers to the LED light failure after a period of light of lamps and lanterns, the light intensity than the initial light intensity decreases, and cannot be restored, the lower part of the LED lamps and lanterns light failure.
(different types of lamps cause different causes of light failure)
In addition, the U.S. energy star lm-80 requires 6000H, and the flux maintenance rate is greater than 94.1%.
Cause of light failure
There is still a lot of debate about the causes of light failure, and the microcosmic mechanism of the decline is still inconclusive, but generally speaking, the light failure of the LED is mainly caused by the heat dissipation problem.
LED afraid of heat is the industry is well known, LED the ideal working temperature is between 5 ° ~ 0 °, but it is basically impossible, hot will affect the droop of LED lamps and lanterns and life, LED at work, there will be about 80% of the electricity into light, LED the radiator is to a LED heat dissipation, because the LED chip at work, its own environmental temperature
The higher the temperature, the lower the light rate. When the temperature reaches the highest temperature of the LED chip, the lamp will be broken.
In addition, the thermal resistance of the LED chip itself, the influence of silver glue, the heat dissipation effect of the substrate, and the colloidal and gold wire are also related to the light failure.
How to solve the luminaire?
In fact, strictly speaking, the LED light lamps and lanterns is an unavoidable failure, it is the common concern of the htac technique problem, but as long as we know the cooling way of lamps and lanterns, can reduce the droop of the biggest problems.
On the market often see the LED lamp heat dissipation structure.
But before we talk about the heat dissipation of LED lamps, we have to understand it: temperature.
What is the junction temperature?
The so-called junction temperature is the working temperature of the PN junction of semiconductor chips (wafers and bare chips). The higher the junction temperature, the earlier the light failure occurs.
If the junction temperature of 105 °, the brightness of 70% life only more than ten thousand hours, 95 hours, 95 ° and the junction temperature down to 75 °, life 50000 hours, 65 ° more can be extended to 90000 hours.
Therefore, the key to prolong life is to reduce the temperature, and the key to reduce the temperature is to have a good radiator, so how can we systematically identify the heat dissipation of LED lamps and lanterns?
The average LED temperature rises and the flux drops.
So, if we measure the illumination of the lamps in the same position, we can reverse the change of the temperature. The specific method is:
Choose a place that is free from outside light, preferably at night and turn off other lights.
2. Turn on the light in a cold state, immediately measure the illumination of a position, and the reading is "cold illumination" at this time.
3. Keep the lamp and illuminometer position unchanged, and the lamps shall continue to work.
4. After half an hour, read the illuminance here and record the reading as "thermal illumination".
5. If the two values are similar (10~15%), the cooling system of this lamp is basically good.
6. If the two values are far apart (greater than 20%), the luminaire cooling system is doubtful.
The "half hour illumination method" is simple to measure the temperature change.
In addition, we should not only think that the radiators are good or bad, but we should choose the most cost-effective ones, rather than the best ones. Therefore, the conclusion is:
1. Hand touch radiator is very hot, must not be good, hand touch radiator not hot, not necessarily good.
2. In the case of reasonable design, the same weight, the surface area is large, the radiator is good.
3. The same surface area, that weight, that radiator is good.
(the premise is the same material)
4. Fin radiators are not the more the better, the more dense the better.
Light failure is a necessary process of lamps and lanterns of work, when we buy lamps and lanterns, be sure to choose quality and heat dissipation performance good lamps and lanterns, in use process should also try to reduce the workload of lamps and lanterns, can delay the speed droop, extend the life of the lamps and lanterns.