LED lamps and lanterns of the cooling quality judgment: illumination measurement in half an hour

Released by the appearance level how high is useless heat quality is the core of the LED lamps and lanterns!" By heat transfer, this paper points out that: judge a lamps and lanterns of radiator do well, the most direct method is to measure the lamps and lanterns to work when the temperature of the LED chip, a technique known as "junction temperature", but this is obviously a theory, when a lamps and lanterns is completed, the junction temperature is hidden, that is why we need to come to the conclusion that so many measurement methods to help determine the cause of the heat dissipation merits. 
Besides the paper points out that the subjective qualitative judgment before, this article introduce a way of quantitative judgment junction temperature can be indirectly. 
"Half an hour of illuminance method" junction temperature measurement 
Since we cannot directly measure the junction temperature, that have indirect methods can be learned that junction temperature? Fortunately, general LED junction temperature rise, high luminous flux will decline. So, we just measure the lamps and lanterns, in the same location illumination changes, can the launch of the junction temperature changes. 
Particular way is: 
1, choose a place without external light interference, had better be in the evening, turn off the other lights. 
2, cold light, measuring a location of the intensity of illumination, immediately write down the readings for the "cold light". 
3, the lamps and lanterns and light meter position unchanged, lamps and lanterns of continuous work. 
4, after half an hour, and then read the illuminance values here, write down the readings for the "hot intensity of illumination. 
5, if the two Numbers about (10 ~ 15%), is the basic of the lamps and lanterns of the cooling system is good. 
6, if the two Numbers are far (greater than 20%), then this lamps and lanterns of the cooling system is questionable. 
General designer or engineering manufacturers have a light meter? What? Has not yet? Go to buy one, and inexpensive, more than 100 yuan can use! 
Just how specific illumination will decline ratio is reasonable? This depends on the specific performance of the specifications of the LED chip, and can't simple proportion specified range. 
"Half an hour of illuminance method" the applicable scope 
We enumerate several commonly used chip "luminous flux vs junction temperature change curve, can see from the curve, how many lumen flux decline, can indirectly to know junction temperature rose to how many degrees Celsius. 

----------Archled Technology Co.,Limited