Thermal Investigation Of Light Emitting Diodes
Author(s)
K. Domke & K. Wandachowicz
Abstract
High power light emitting diodes are already a popular alternative to
incandescent and fluorescent lamps and it seems that in around a dozen years or
so they may become the basic type of lamp used in lighting engineering. In
addition to emitting light, LEDs also generate a significant quantity of heat. The
assumption is that ca. 75% of total power is released in the form of heat which
must be carried into the environment. Heat released in the p-n junction of the
semiconductor material markedly increases its temperature and thus indirectly
affects the photometric and electric characteristics of LEDs. The paper below
presents a test stand designed for measuring such characteristics for a wide range
of changes of junction temperatures. Junction temperature adjustment can
proceed independently of the thermal power released in the LED. Selected
measured characteristics of HP LEDs are also presented.
Keywords: light emitting diode, junction temperature, photometric measurement.
1 Introduction
Semiconductor LEDs made in the solid state lightning (SSL) technology can be
divided into low power (LEDs) and high power (HP LEDs). The latter represent
the most advanced group of light sources used in the lighting industry for general
and decorative lighting applications and in the automotive industry for marker
lights, stop lights, direction indicator lights and car headlights. The LED market
is now a major and rapidly developing segment of the electronics market.
Forecast growth of the LED technology (published in 2002) is presented in
table 1 (supplemented by 2007 data).
In the LED markets White High Brightness LEDs will fuel growth to surpass
$14 billion by 2017. The present LED market by value is as in table 2:
The manufacturing technology of light emitting diodes has been growing
exponentially in recent years. Different types and forms of LEDs have varied
Keywords
light emitting diode, junction temperature, photometric measurement.
Related Book
Other papers in this volume
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