light decay for LED lighting products
LED Light are take as a new type of green lighting, energy saving and long life span. but the light decay will affect the usage of lamps.
What is Light decay?
light decay refers to the lumen flux will be lower than origin after lamp use in a period, the part of lower is called light decay.
with the time of usage, all light source will reduce its brightness compared to initial time. before led lighting products reach its end of life, the acceptable light decay is 50%-60%.
How much light decay for led tube?
For led tube, its light decay within 10% is qualified after 1000 hours, normally high quality led tube can keep 70% after 50000 hours.
What reason caused light decay?
there are many factors cause the light decay, but the main factor is heat dissipation. normally ordinary epoxy resin have limited thermal conductivity coefficient, so when you test the leds bracket temperature is 45 degree, but its inner chip center temperature maybe exceed 80 degree. actually leds temperature junction is 80 degree, so the lamp will speed up attenuation when leds chip work under its junction temperature.
1. led lighting products Quality problems
1) the brightness will rapidly reduce if use poor quality leds and aluminum shells.
2) due to defective production process, leds wafer can not have good heat dissipation, it will cause high temperature to intensify the attenuation.
2. leds working environment
according to aging data of single leds, if only one leds is in working under 30 degree environment, then its leds bracket temperature will not exceed 45 degree. at this time, leds life span is good.
if there are 100pcs leds working in same time, the space is 11.4mm between them, then the both side leds bracket temperature also may not exceed 45 degree, but the middle leds may reach in high temperature of 65 degrees. then Theoretically, the middle leds will have quick light decay than its surroundings.
anyway, we should know that the higher temperature, the shorter life of led.
3. leds technical parameters and encapsulation
According to testing result, the less heat will be caused when leds in lower current. leds encapsulation materials and leds chip size also will affect the whole lamp’s light decay. overall, we need to comprehensive consider these factors.