Abstract
LED-based lamps that are currently on the market are expensive due to the complex
packaging required to dissipate the heat generated. This also limits their performance
and lifetime due to the degradation of the phosphor or individual LED chips, in the case
of RGB sources. There is a strong commercial imperative to develop <i>in situ</i>
technology to measure and ultimately compensate for the thermal environment of a
luminaire.Utilizing the large Stoke's shift in InGaN green and blue emitting LEDs, a
blue LED emitter pump can induce a photocurrent within devices which emit in either the
blue or green region. Measurements have shown that green and blue emitters may be
excited on the absorption edge in an effect which results in a rise in the open circuit
voltage with increasing temperature. From these measurements the junction temperature of
a device operating in quasi-cw mode at 80 mA is shown to result in a junction
temperature of 86 (±2) °C which agrees well with a junction temperature of 87
(±2) °C measured using the more conventional forward voltage
technique.This paper describes the technique utilized and the results achieved in
driving a green emitting LED with a blue emitting pump LED and furthermore it discusses
some of the benefits and issues associated with this technique for determining the
junction temperature.
© 2013 IEEE
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