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2016August

Discussion on the heat production of

From: www.szbako.com Data:08/08/2016

and traditional light source, the semiconductor light-emitting diode (LED) in the course of work will generate heat, which depends in the overall luminous efficiency. Under the external electrical energy, electron and hole radiative recombination electroluminescence occurs, in the p-n junction near radiating light need after chip (chip) of semiconductor media and media package can be arrived at the outside (air). Current injection efficiency, emission and luminescence quantum efficiency, chip and external light extraction efficiency, eventually may only 30-40% of the input power can be transformed into light energy, the remaining 60% to 70% of energy mainly in the form of non radiative recombination occurs the lattice vibration of conversion of heat.

chip temperature increases, will increase the non radiative recombination, and further weaken the luminous efficiency. Because, it is subjective that high power LED no heat, in fact there are. A lot of heat, as well as in the use of problems in the process. Coupled with a lot of people who first use high power LED, the thermal problem does not understand how to effectively solve the problem, making the product reliability has become the main problem. Then, LED whether there is no heat generated it? How much heat can be generated? How much heat is the heat generated by LED? Under the forward voltage, the electron can get energy from the power supply. Under the driving of the electric field, the electric field of the electric field is overcome, and the N region of the P region is excited by the

LED region, which is combined with the hole in the P region. Due to the drift of the free electrons in the P region, the energy of the valence electrons in the P region is higher than that of the electron back to the low energy state, and the excess energy is released in the form of photons. The wavelength of the photon is related to the energy difference Eg. It is seen that the luminescence zone is mainly near the light emitting region, and the luminescence is due to the recombination of electrons and holes. A semiconductor diode, electrons in the semiconductor region to enter all the distance away from the semiconductor region, will encounter resistance. Simply from the principle of see, the physical structure of the semiconductor diode simply from the principle of see, the electrons emitted by the semiconductor diode with the physical structure of the source cathode and back to the cathode of the electron number is equal to the. Ordinary diode, in the event of electron hole pairs of composite is, due to the factors of differential eg, the release of photon spectra in the visible range.

electronics in diode internal way, are due to the presence of resistance and power consumption. The consumption of power line with electronics of the basic law:
P = I2 r = I2 (RN + + RP) + IVTH
type RN is PN junction opening voltage
RP is P body resistance
consumption power to generate heat for n body resistance
VTH:
Q = Pt
type: t for diode energized.

essence, LED is a semiconductor diode. Therefore, LED in the positive work, its working process in accordance with the above described. It it consumes the electric power:
P led u = LED & times; I LED
: u LED is on both ends of the LED light source of the forward voltage
I LED is flowing through the LED current
the consumption of electric power conversion into heat release:
Q = P LED & times; t
: t is through electrical time

LED has nothing to do with the light efficiency; there is no one percent of the electric power to produce light, and the remaining percent of the electric power is generating heat. Through the understanding of the generation, thermal resistance and junction temperature of high power LED thermal and the derivation of theoretical formula and the measurement of thermal resistance, we can study the design, evaluation and application of high power LED. Need to explain is thermal management is led luminous efficiency is not high at the present stage of the key issues in, from fundamentally improve the luminous efficiency in order to reduce the heat generated is drastic move, which requires chip manufacturing, packaging and LED application products various aspects of technical progress and development.

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