Theory of filament lamp, filament scattered "hot"
- Sep 18, 2016 -
As is known to all, now LED a filament lamp still there are some technical bottlenecks, heat dissipation is one of them, in order to seek the long-term development, the attack is only a matter of time.
When it comes to leds, especially filament, always inseparable from the "hot" in this industry.
Here, we focus on talk filament "hot" those things, first understand the relationship between the heat and the LED.
Hot relationship with leds are the following:
LED under different junction temperature, its life is different, the lower the junction temperature exponential rise in life, as shown in the figure below:
2. The LED junction temperature is 25 degrees of luminescence is 100%, then the junction temperature rise to 60 degrees, the count was only 90%; Junction temperature is 100 degrees when it fell to 80%; 140 degrees is only 70%. Visible to improve heat dissipation, junction temperature control is very important thing.
3. Besides the LED fever will make the spectrum of mobile; High colour temperature rise; When forward current increases (constant voltage power supply); Reverse current also increases; The thermal stress increases; Phosphor problems in the accelerated aging of epoxy resin, etc.
If you still feel the abstract, think about why the LED light test luminous flux and high light efficiency, can be measured again later, parameters are lower!
Filament heat dissipation problem was discussed before, the popular science the cooling method, it is necessary to this, saying: knife don't miss your job!
Analysis of cooling, must understand the structure of the filament lamp, below is common A60 filament lamps on the market, often do about 5 w power.
It basically has the following several parts of glass bubble column shell, glass, wire, filament, power and lamp holder.
General glass thermal conductivity is 0.07 ~ 2 W/mK, general gas thermal conductivity coefficient is 0.01 ~ 0.2 W/mK, the coefficient of thermal conductivity of copper 377 W/mK, coefficient of thermal conductivity of iron around 50 W/mK.
Mentioned earlier there are three types of heat transfer way, for the filament lamp is no exception. The following three is the conduction, convection and radiation calculation formula:
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