How to tell whether the heat dissipation of the lamp is good or not?
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Author : Crownda.LED
Update time : 2021-08-14 12:01:12
How to tell whether the heat dissipation of the lamp is good or not?
When we deal with the sales side of a lighting company, we normally repeatedly mention a word: quality assurance.
The warranty period declared by each LED lights manufacturer is different. There are two-year warranty, three-year warranty, five- year warranty and seven-year warranty.
However, in many cases, the LED fixture sellers themselves do not understand how this warranty period is derived, or are they just following the trend that LEDs should be warranted for such a long period of time?
Today, let's take you into the world of LEDs and explore how the life of LED lamps is defined and judged.
First of all, when it comes to LEDs, in terms of appearance, we can tell the difference from traditional light sources at a glance, because almost all LEDs have a distinctive feature-a heat sink. All kinds of heat sinks are not for the aesthetics of LED lights, but for making LEDs work better.
Then you must be wondering, why did the previous light sources use fewer radiators, but almost all lamps in the LED era used radiators?
That's because the traditional light sources all relied on thermal radiation to emit light, such as tungsten filament lamps, which relied on heat to emit light, so they were not afraid of heat. The basic structure of the LED is a semiconductor P-N junction. A slightly higher temperature will reduce the performance of the LED. Therefore, heat dissipation is very important for the LED.
First of all, let us take a look at the LED composition and schematic diagram.
Tips: LED chips will generate heat when they are working. We call the temperature of its internal PN junction as junction temperature.
In our daily life, the luminous flux of the LED will decrease as the junction temperature increases. As shown in the figure, when the junction temperature is 25℃ as the standard value, when the junction temperature reaches 100℃, the luminous flux is about 80%.
Moreover, the most important thing is that the life of LED luminaires is closely related to the junction temperature. One concept that needs to be understood is: when we talk about the life of an LED, we do not mean that it burns out at the end of its life. Generally, when the light output of an LED reaches 70%, we consider it to be over.
It can be seen from the figure above that if the junction temperature is controlled at 105°C, the luminous flux of the LED bulb will be reduced to 70% after about 10,000 hours. And if the junction temperature is controlled at about 60°C, the luminous flux will be reduced to 100000+ hours. The light will attenuate to 70%. The life span has increased by 10 times.
In daily life, what we most often encounter is that the life of the LED is 50,000 hours, which is actually a data when the junction temperature is controlled at 85°C. Since junction temperature plays such an important role in the life of LED products, how to reduce junction temperature? Don't worry, let's take a look at how the lamp dissipates heat first. After understanding the heat dissipation method, you will naturally know how to reduce the junction temperature.
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