| Summary: | 碩士 === 元智大學 === 機械工程學系 === 95 === Investigations of thermal characteristics of Red, Green, Blue LED and White LED and diffusion area for the LED module were conducted experimentally. Results show that red LED has lower internal resistance than that of green and blue. However, green LED shows higher luminous flux than the others. The luminous flux of blue LED is only one fifth than that of green LED, its lighting power energy is closed to green LED. In these three kinds of lighting LED, red LED is more sensitive to the thermal environment. Red lighting efficiency will decrease almost 12% when the substrate temperature increases 25℃.
From the White LED result, The luminous flux and UV Energy are relative to temperature, and the spectrum doesn’t have any departure. For 2W input power, 5W LED have better thermal characteristics .To compare different packaging LED, YAG LED have better effect than RGB LED on the same input power.
Thermal diffusion experimental results show a closed correlation between thermal power and diffusion area of module. If the up limit temperature of LED substrate is 70℃, for a 500 cm2 area, the higher limit of electric power is 14.3 watts. Diffusion processes for LED substrate to environment include thermal conduction and convection. Thermal convection will dominate as increasing surface temperature of thermal module.
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