CN104792434A - Device and method for representing GaN-based LED junction temperature by centroid wavelength and spectral width - Google Patents

Abstract

The invention discloses a device and a method for representing a GaN-based LED junction temperature by a centroid wavelength and a spectral width. The device comprises a thermal resistant structure analyzer, a thermostat and an integrating sphere, wherein an LED lamp seat, a spectrum analyzer and a computer are arranged on the thermostat, the signal transmission end of the spectrum analyzer is connected with the computer, a spectrum analyzer probe is arranged in the integrating sphere and reaches to the inner wall of the integrating sphere by penetrating through the integrating sphere, an LED light source mounted on the LED lamp seat is connected to the thermal resistant structure analyzer and penetrates into the integrating sphere, and a driving power source is connected to the computer. The device and the method for representing the GaN-based LED junction temperature by the centroid wavelength and the spectral width have the advantages that the method and the device for measurement are accurate, reliable, convenient and simple, and the GaN-based LED junction temperature can be measured by the simple and efficient device at low use cost and without contacting with an LED.

Description

A kind of centroid wavelength combined spectral width characterizes the devices and methods therefor of GaN base LED junction temperature

Technical field

The present invention relates to LED photovoltaic pick-up unit and method thereof, particularly a kind of centroid wavelength combined spectral width characterizes the devices and methods therefor of GaN base LED junction temperature.

Background technology

LED (Light Emitting Diode) has been widely used in the fields such as signal designation, liquid crystal backlight, display, general illumination.But, the photoelectric color characteristic of LED self and life-span and junction temperature closely related.Junction temperature rising can cause the luminescence efficiency of LED to reduce, the lost of life.Therefore how fast, science, easily measurement LED junction temperature just become the breach of problem.

The LED junction temperature measurement method reported has forward voltage method (EIA/JEDEC standard JESD51-1, Chinese Industrial Standards (CIS) 200910198965.5, Chinese patent 200920212653.0,200910198965.5), heat resistance method (standard SJ/T11394-2009), [by measuring the thermal power of LED pipe pin temperature and chip cooling, and thermal resistivity determines junction temperature, need in measurement in conjunction with forward voltage method to determine thermal resistivity.] peak wavelength method [Third International Conference on Solid StateLighting, Proceedings of SPIE 2010.5187:93-99], valley wavelength method [spectroscopy and spectral analysis, 2013,33 (1): 36-39], radiation intensity method [optoelectronic laser, 2009,20 (8): 1053-1057], blue Bai Bifa [Thirdinternational conference on solid state lighting, proceedings of SPIE 2010.5187:107-114].Liquid crystal array thermal imaging method [Phys.Stat.Sol (c) 1 (2004) 2429], Micro-Rpectra method [Phys.Status.Solidi, A202 (2005) 824], luminescence spectroscopy [Appl.Phys.Lett.89 (2006) 101114]. centre wavelength method (Microelectronics Reliability, 2013,53 (5): 701-705) and centroid wavelength method (CN201410268725).

But, these methods are measured GaN base LED junction temperature and still be there is many deficiencies, as the restriction due to its lamp outer casing material etc., general being difficult to realizes the drop measurement on a symbol LED pin, forward voltage method is difficult to use, peak wavelength method, and centroid wavelength method and valley wavelength method need Measurement accuracy peak value or valley, more disadvantageously, the peak wavelength of GaN base LED and the relation of junction temperature not dull.Blue Bai Bifa can only be used for fluorescent powder conversion hysteria White LED junction temperature, radiation intensity method to measurement environment and conditional request higher, liquid crystal array thermal imaging method, Micro-Rpectra method, luminescence spectroscopy etc. are high to the accuracy requirement of testing tool, and relevant device costly.

When curent change is little, the width of GaN base LED light spectrum is dull with the increase of junction temperature to be increased, and therefore, full width at half maximum can be used to characterize junction temperature, weighting full width at half maximum also can be used to characterize GaN base LED junction temperature, see patent CN201410268532.But when curent change is larger, the error that full width at half maximum or weighting full width at half maximum characterize junction temperature is comparatively large, therefore, other new methods based on spectral distribution of necessary exploitation, i.e. centroid wavelength combined spectral width method.

Summary of the invention

1. the technical matters that will solve

For problems of the prior art, the invention provides a kind of based on GaN base LED module spectral characteristic accurately and reliably, facilitate succinct measurement mechanism and method, its use cost is lower, device is simple efficient does not contact the junction temperature that LED itself can measure GaN base LED simultaneously.

2. technical scheme

Object of the present invention is achieved through the following technical solutions.

A kind of centroid wavelength associating full width at half maximum characterizes the device of GaN base LED junction temperature, comprise thermal resistance structure analyser, thermostat, integrating sphere, described thermostat is provided with LED seat and spectroanalysis instrument and computer, the Signal transmissions end of described spectroanalysis instrument is connected with computer, spectral analysis instrument probe is provided with in described integrating sphere, described spectral analysis instrument probe arrives integrating sphere inwall through integrating sphere, described thermal resistance structure analyser is connected with LED light source, described LED light source arrives in integrating sphere through the hole of integrating sphere, described computer is connected with driving power, described LED light source is placed on LED seat.

Described LED light source refers to GaN base list LEDs or LED array, and described LED array is made up of different colours GaN base LED.

Centroid wavelength associating full width at half maximum characterizes a method for GaN base LED junction temperature, comprises the following steps:

1) will the LED light source demarcated be needed to be arranged on the LED seat on thermostat, the thermo-contact that both maintenances are good, described LED light source enters integrating sphere inside surface by the hole of integrating sphere side, spectral analysis instrument probe enters integrating sphere inwall by the hole of integrating sphere opposite side, described spectroanalysis instrument data output end is connected with computer, the control end of described thermal resistance structure analyser is connected with computer, and the power output end of described thermal resistance structure analyser is connected with LED seat;

2) through step 1) after thermostat temperature T is set ₁, after LED light source reaches the thermostat temperature of setting, adjust driving power, make LED light source luminous under the electric current being less than rated current 5% drives, then measure the relative spectral of LED light source with spectroanalysis instrument, and by relative spectral power distribution under computer record;

3) step 2 is repeated), measurement thermostat temperature is T ₂time LED light source relative spectral power distribution;

4) formula is passed through calculate the centroid wavelength that different thermostat temperature is corresponding, wherein λ ₁, λ ₂the upper and lower limit wavelength of LED light Spectral structure, by formula Δ λ _0.5=λ _up-λ _downcalculate the full width at half maximum that different thermostat temperature is corresponding, wherein λ _up, λ _downlarger and the less wavelength that peak value half that to be spectrum be respectively is corresponding, namely measuring tempeature controller temperature is T ₁and T ₂time, centroid wavelength is respectively full width at half maximum is respectively utilize formula calculate centroid wavelength-junction temperature COEFFICIENT K and full width at half maximum-junction temperature coefficient k ^/;

5) change underlayer temperature and drive current, making junction temperature constant is T ₀, measure normalization spectral power distribution now, and calculate centroid wavelength and full width at half maximum pass through formula $\mathrm{\Δ}{\mathrm{\λ}}_{0.5}^3={\mathrm{\σ}}_0^{/}+{\mathrm{\σ}}_1^{/}\exp (I_f/I_0^{/}),$ Adopt least square fitting, obtain factor sigma ₀, σ ₁, I ₀and

6) relative spectral power distribution of LED light source under normal running conditions is measured, through type Δ λ _0.5=λ _up-λ _downcalculate centroid wavelength and full width at half maximum, measure measures ambient temperature T ₀, substitute into formula ${\left[\frac{{\mathrm{\λ}}_c-k(T_j-T_0)-{\mathrm{\σ}}_0}{{\mathrm{\σ}}_1}\right]}^{I_0}={\left[\frac{\mathrm{\Δ}{\mathrm{\λ}}_{0.5}-k^{/}(T_j-T_0)-{\mathrm{\σ}}_0^{/}}{{\mathrm{\σ}}_1^{/}}\right]}^{I_0^{/}}$ The junction temperature of the LED light source to be measured obtained.

3. beneficial effect

Compared to prior art, the invention has the advantages that:

1, single is demarcated, repetitive measurement.Namely for LED module, only need to demarcate coefficient of first order σ ₀, σ ₁, I ₀, k and when measuring the junction temperature under different lighting condition, all can adopt the result of demarcating.

2, only need conventional opto-electronic testing apparatus.

3, centroid wavelength and the easy Measurement accuracy of full width at half maximum, the repeatability of measurement is high, little for characterizing junction temperature error.

4, do not contact LED pin during measurement, avoid destroying thermal environment.

5, may be used for single LEDs junction temperature measurement, the average junction temperature that also may be used for the array of many GaN base LED compositions is measured, and usable range is wide.

Accompanying drawing explanation

Fig. 1 is the structural representation of calibrating installation of the present invention;

Fig. 2 is the schematic diagram of measurement mechanism;

The curve of centroid wavelength and full width at half maximum when Fig. 3 is different junction temperature;

Fig. 4 is the process flow diagram characterizing LED junction temperature with centroid wavelength associating full width at half maximum.

In figure: 1, thermal resistance structure analyser, 2, thermostat, 3, integrating sphere, 4, LED seat, 5, spectroanalysis instrument, 6, computer, 7, LED light source, 8, driving power.

Embodiment

Below in conjunction with Figure of description and specific embodiment, the present invention is described in detail.

Embodiment 1

As shown in Figure 1, a kind of centroid wavelength associating full width at half maximum characterizes the device of GaN base LED junction temperature, comprise thermal resistance structure analyser 1, thermostat 2, integrating sphere 3, described thermostat 2 is provided with LED seat 4 and spectroanalysis instrument 5 and computer 6, the Signal transmissions end of described spectroanalysis instrument 5 is connected with computer 6, be provided with spectroanalysis instrument 5 in described integrating sphere 3 to pop one's head in, described spectroanalysis instrument 5 is popped one's head in and is arrived integrating sphere 3 inwall through integrating sphere 3, described thermal resistance structure analyser 1 is connected with LED light source 7, described LED light source 7 arrives in integrating sphere 3 through the hole of integrating sphere 3, described computer 6 is connected with driving power 8, described LED light source 7 is placed on LED seat 4.

As shown in Figure 2, LED light source 7 measured by spectroanalysis instrument 5.

The effect of thermal resistance structure analyser 1 adopts voltage method to measure LED junction temperature, and provide stable power supply for LED light source 7.

Described LED light source 7 refers to GaN base list LEDs or LED array, and described LED array is made up of different colours GaN base LED.

As shown in Figure 4, a kind of centroid wavelength associating full width at half maximum characterizes the method for GaN base LED junction temperature, comprises the following steps:

1) demarcate: be arranged on the LED seat 4 on thermostat 2 by needing the LED light source 7 demarcated, the thermo-contact that both maintenances are good, described LED light source 7 enters integrating sphere 3 inside surface by the hole of integrating sphere 3 side, spectroanalysis instrument 5 is popped one's head in and is entered integrating sphere 3 inwall by the hole of integrating sphere 3 opposite side, described spectroanalysis instrument 5 data output end is connected with computer 6, the control end of described thermal resistance structure analyser 1 is connected with computer 6, and the power output end of described thermal resistance structure analyser 1 is connected with LED seat 4;

2) through step 1) after thermostat 2 temperature T is set ₁it is 20 DEG C, driving power 8 is adjusted after LED light source 7 reaches thermostat 2 temperature of setting, make LED light source 7 luminous under the electric current being less than rated current 5% drives, then measure the relative spectral of LED light source 7 with spectroanalysis instrument 5, and record relative spectral power distribution by computer 6;

3) step 2 is repeated), measuring thermostat 2 temperature is T ₂the relative spectral power distribution of LED light source 7 when being 70 DEG C;

4) formula is passed through calculate the centroid wavelength that different thermostat 2 temperature is corresponding, wherein λ ₁, λ ₂be the upper and lower limit wavelength of LED light Spectral structure, for visible LED, generally get 380nm and 780nm.Full width at half maximum Δ λ _0.5be defined as the difference that spectral power distribution is wavelength corresponding to the half of peak height, by formula Δ λ _0.5=λ _up-λ _downcalculate the full width at half maximum that different thermostat 2 temperature is corresponding, wherein λ _up, λ _downlarger and the less wavelength that peak value half that to be spectrum be respectively is corresponding, drive current is set to rated current, and measuring tempeature controller temperature is T ₁and T ₂time, the normalization spectral power distribution of LED, namely measuring tempeature controller temperature is T ₁and T ₂time, centroid wavelength is respectively full width at half maximum is respectively utilize formula calculate centroid wavelength-junction temperature COEFFICIENT K (3.64) and full width at half maximum-junction temperature coefficient k ^/(5.48);

5) change underlayer temperature and drive current, making junction temperature constant is T ₀be 50 DEG C, measure normalization spectral power distribution now, as shown in Figure 3, and calculate centroid wavelength and full width at half maximum

Pass through formula ${\mathrm{\λ}}_c^3={\mathrm{\σ}}_0+{\mathrm{\σ}}_1\exp (I_f/I_0),\mathrm{\Δ}{\mathrm{\λ}}_{0.5}^3={\mathrm{\σ}}_0^{/}+{\mathrm{\σ}}_1^{/}\exp (I_f/I_0^{/}),$ Because equation number is generally far more than unknown number, can least square fitting be adopted, obtain factor sigma ₀, σ ₁, I ₀and (being respectively 460.7,5.16,429.5 and 23.8,3.0,403.9);

6) relative spectral power distribution of LED light source 7 under normal running conditions is measured, through type Δ λ _0.5=λ _up-λ _downcalculate centroid wavelength 465nm and full width at half maximum 21.3nm, measure measures ambient temperature T ₀be 30 DEG C, substitute into formula ${\left[\frac{{\mathrm{\λ}}_c-k(T_j-T_0)-{\mathrm{\σ}}_0}{{\mathrm{\σ}}_1}\right]}^{I_0}={\left[\frac{\mathrm{\Δ}{\mathrm{\λ}}_{0.5}-k^{/}(T_j-T_0)-{\mathrm{\σ}}_0^{/}}{{\mathrm{\σ}}_1^{/}}\right]}^{I_0^{/}},$ The junction temperature of the LED light source to be measured 7 obtained is 61.4.

Claims (3)

1. one kind characterizes the device of GaN base LED junction temperature with centroid wavelength associating full width at half maximum, comprise thermal resistance structure analyser, thermostat, integrating sphere, it is characterized in that: described thermostat is provided with LED seat and spectroanalysis instrument and computer, the Signal transmissions end of described spectroanalysis instrument is connected with computer, spectral analysis instrument probe is provided with in described integrating sphere, described spectral analysis instrument probe arrives integrating sphere inwall through integrating sphere, described thermal resistance structure analyser is connected with LED light source, described LED light source arrives in integrating sphere through the hole of integrating sphere, described computer is connected with driving power, described LED light source is placed on LED seat.

2. a kind of centroid wavelength associating full width at half maximum according to claim 1 characterizes the device of GaN base LED junction temperature, and it is characterized in that described LED light source refers to GaN base list LEDs or LED array, described LED array is made up of different colours GaN base LED.

3. characterize a method for GaN base LED junction temperature with centroid wavelength associating full width at half maximum, it is characterized in that comprising the following steps:

1) will the LED light source demarcated be needed to be arranged on the LED seat on thermostat, the thermo-contact that both maintenances are good, described LED light source enters integrating sphere inside surface by the hole of integrating sphere side, spectral analysis instrument probe enters integrating sphere inwall by the hole of integrating sphere opposite side, described spectroanalysis instrument data output end is connected with computer, the control end of described thermal resistance structure analyser is connected with computer, and the power output end of described thermal resistance structure analyser is connected with LED seat;

2) through step 1) after thermostat temperature T is set ₁, after LED light source reaches the thermostat temperature of setting, adjust driving power, make LED light source luminous under the electric current being less than rated current 5% drives, then measure the relative spectral of LED light source with spectroanalysis instrument, and by relative spectral power distribution under computer record;

3) step 2 is repeated), measurement thermostat temperature is T ₂time LED light source relative spectral power distribution;

4) formula is passed through ${\mathrm{\λ}}_c=\frac{\underset{{\mathrm{\λ}}_1}{\overset{{\mathrm{\λ}}_2}{\∫}}F\left(\mathrm{\λ}\right)\·\mathrm{\λd\λ}}{\underset{{\mathrm{\λ}}_1}{\overset{{\mathrm{\λ}}_2}{\∫}}F\left(\mathrm{\λ}\right)\mathrm{d\λ}}$ Calculate the centroid wavelength that different thermostat temperature is corresponding, wherein λ ₁, λ ₂the upper and lower limit wavelength of LED light Spectral structure, by formula Δ λ _0.5=λ _up-λ _downcalculate the full width at half maximum that different thermostat temperature is corresponding, wherein λ _up, λ _downlarger and the less wavelength that peak value half that to be spectrum be respectively is corresponding, namely measuring tempeature controller temperature is T ₁and T ₂time, centroid wavelength is respectively full width at half maximum is respectively utilize formula calculate centroid wavelength-junction temperature COEFFICIENT K and full width at half maximum-junction temperature coefficient k ^/;

5) change underlayer temperature and drive current, making junction temperature constant is T ₀, measure normalization spectral power distribution now, and calculate centroid wavelength and full width at half maximum pass through formula adopt least square fitting, obtain factor sigma ₀, σ ₁, I ₀and

6) relative spectral power distribution of LED light source under normal running conditions is measured, through type Δ λ _0.5=λ _up-λ _downcalculate centroid wavelength and full width at half maximum, measure measures ambient temperature T ₀, substitute into formula ${\left[\frac{{\mathrm{\λ}}_c-k(T_j\·T_0)-{\mathrm{\σ}}_0}{{\mathrm{\σ}}_1}\right]}^{I_0}={\left[\frac{{\mathrm{\Δ\λ}}_{0.5}-k^{/}(T_j\·T_0)-{\mathrm{\σ}}_0^{/}}{{\mathrm{\σ}}_1^{/}}\right]}^{I_0^{/}},$ The junction temperature of the LED light source to be measured obtained.