Thermal radiation, heat conduction and heat
management and use of bright LED's users (especially the automotive
industry), the key issues facing the one with the biggest challenges is
the LED self-heating problem. LED lumens per watt has made significant
improvements, but the fact is that the majority of LED power were
converted to heat conduction. LED has the advantages of low radiant
heat, suitable for car lighting. On the contrary, in cold weather, the
headlights of the radiant heat is effective in melting snow on the
lens. Therefore, the thermal management is the key to effective control
of LED. Thermal control mainly refers to the temperature increase,
reduce current. The use of bright LED advantage is that current changes
is larger, the eye can not detect the brightness changes. In general,
the current decreased by 25%, the single LED's brightness change is not
obvious. However, LED will change with temperature and current to
change the color characteristics, this will affect the automotive
lighting applications is still unclear. The applicability of the
spectrum LED lighting, night-vision effect in general will affect the
driver under the sense of distance, these problems may be even more
important. Using PWM method to reduce the brightness ratio, rather than
the direct current control, receive a greater brightness and color
temperature does not change the ratio, it is a better method of PWM
dimming.
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