of the white LED, T8 Tube
21/10/2013 08:48
Figure 7 GaInN -based LED quantum efficiency and current density in
The conventional white LED is a side length of 200 ~ 350μm square chip package into round pillar shape , and then to obtain a desired beam illumination , and then packaged in a plurality of white LED components arranged in a matrix shape. Simply to high output power developed specifically for the purpose of large chip area than in the past 6-10 times , dimensions up to 500μm ~ 1mm of the white LED, T8 Tube
although the package is given to several hundred milliwatts ( tens of lumens) output power, However, increasing the chip size, but to make white LED interior light absorption ratio increased , the external light extraction rate. Take AlGaInP LED , for example, the chip dimensions increase as from 0.22mm × 0.22mm 0.50mm × 0.50mm ,
the external light extraction rates have decreased about 20%. TIP If the switch structure, the internal multiple reflections result that the internal light absorption rate , the external light extraction efficiency is significantly improved. GaInN LED have the same effect . How to improve the outside of the LED chip LED light extraction efficiency is the key used in general lighting applications . LED Flexi
In addition, the high thermal impedance (150 ~ 200K / W) for high light output quite negative . LED internal quantum efficiency of the temperature dependence of the active layer is great , so in addition to low thermal resistance packaging technology , the use of heat sinks exclude active layer heat flow become the next hot research and development .
