CN103411702A - Device for non-contact measurement of junction temperature of white LED by use of peak wavelength displacement method - Google Patents
Device for non-contact measurement of junction temperature of white LED by use of peak wavelength displacement method Download PDFInfo
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Abstract
The invention discloses a device for fast non -contact measurement of junction temperature of white LED by use of a peak wavelength displacement method. The device includes a measurement system and a calibration system. The measurement system includes a white LED light source (1) to be measured, a spectrometer (2) used for specifically measuring blue wavelength displacement and a computer (3). The spectrometer is composed of a spherical mirror (10), an entrance slit (11), a plane grating (12), an exit slit (13), a CCD (14) and a drive circuit (15). The measurement system is characterized in that a measuring wavelength range is from 440nm to 480nm and the accuracy is better than 0.02nm. The calibration system comprises a temperature controller (4), a thermostat (5), a calibration LED (6), an LED lamp holder (7), a pulsed current source (8), a spectrometer (2) and a computer (3). Through calibration of a peak wavelength-junction temperature coefficient K of the high-power white LED, displacement amount of the peak wavelength when the LED actually works is measured, and the junction temperature under working conditions of the white LED light source to be measured is thus obtained with an accuracy of the junction temperature up to 0.1 DEG C.
Description
Technical field
The present invention relates to the detection technique of semiconductor light-emitting-diode (LED), relate in particular to a kind of LED chip internal junction temperature measurement instrument.
Background technology
The appearance of high-brightness LED is with historically new significance, it will be the mankind's one of greatest inventions after the Edison invented incandescent lamp bulb, be called as the 4th generation lighting source or green light source, with conventional light source, compare, it has lot of advantages: light efficiency is high, without mercury environmental protection, the characteristics such as the life-span is long, volume is little, has been widely used in the special lighting fields such as various indications, demonstration, decoration, backlight, urban landscape.The luminosity factor of LED only can reach 10%-30% at present, has simultaneously the energy conversion of 70%-90% to become heat energy.The raising of high-performance white light LEDs optical property and reliability, all depend on the junction temperature of chip.Therefore how to monitor junction temperature, especially online harmless junction temperature monitoring, may restrict white light LEDs application and problem anxious to be resolved with regard to becoming.
The basic structure of LED is a semi-conductive P-N knot.When electric current flows through the LED element, the temperature of P-N knot will rise, on stricti jurise, say, just the temperature in P-N interface is defined as to the junction temperature of LED. therefore usually because element chip all has very little size, undemanding place also can be junction temperature to what the temperature of LED chip was looked sometimes.The chip size of white light LEDs is little, current density is large, so the temperature rise caused is apparent in view.And in its luminescent spectrum, do not comprise infrared part, and so the heat that device produces can not rely on heat radiation to discharge, the 70-90% left and right of input electric energy is transformed into heat, these heat major parts all are converted into the energy that the chip self-temperature is raise.For semiconductor devices, the variation of temperature, its characteristic has obvious variation.Great power LED particularly, this impact will be more obvious, and chip temperature directly has influence on the luminescence efficiency of LED, predominant wavelength and serviceable life.Have data to show, about 70% LED product bug is too high from junction temperature.And in the situation that being 20 ℃ of faults of the every rising of half temperature of rated power, load just rises one times.Therefore junction temperature how to measure rapidly and accurately LED can help us more reasonably to carry out the LED structural design and optimize LED illuminating engineering heat dissipation design.
At present, the method for measuring the white light LEDs junction temperature mainly contains: 1, forward voltage method, utilize LED electricity delivery temperature effect, and under the condition of steady current, obtain the linear relationship of forward voltage and junction temperature; 2, pin method, utilize the power ratio of blue light and white light in the luminescent spectrum of LED to measure.These methods all belong to contact type measurement, are confined to the junction temperature measurement of single tube LED device.Also there is now the researcher to propose some contactless junction temperature measurement methods: blue Bai Bifa, infrared photography method and peak wavelength method.Because the usable range of these methods is limited, and ratio of precision is lower.The peak wavelength method, utilize the peak value of the luminescent spectrum of LED to increase along with the rising of junction temperature.But due to the junction temperature peak wavelength drift cause little that raises, when raising 10 ℃ the time, peak wavelength changes about 1.4nm left and right, must bring no small error to test result like this, if adopt conventional high-precision spectrometer, can greatly increase testing cost.
Therefore, need a kind of contactless, high precision of design, low cost, and white light LEDs junction temperature measurement instrument simple to operation.
Summary of the invention
In view of the deficiency of said method and technology, the purpose of type of the present invention is to utilize that peak wavelength displacement method design is a kind of has high precision, low cost, a large power white light LED junction temperature measurement device easy and simple to handle.
In order to realize the purpose of type of the present invention, intend adopting following technology:
A kind of quick non-cpntact measurement white light LEDs junction temperature measurement device, it is characterized in that: this system is comprised of calibration and measurement two parts, during calibration, calibration LED (6) is arranged in constant temperature oven (5), with a light-conductive optic fibre (9), will calibrate the light that LED (6) sends and be transmitted to the spectroanalysis instrument (2) that special survey blue light wavelength is shifted.By the computing machine (3) be connected on spectrometer (2), obtain the peak wavelength at this temperature, and obtain the peak wavelength of this calibration LED-junction temperature COEFFICIENT K, initial junction temperature T by multi-group data
aAnd initial spike wavelength X
a.During measurement, by spectrometer (2), directly measure LED to be measured (1) peak wavelength in normal operation, in conjunction with formula
Calculate fast the junction temperature of LED to be measured under this duty.
Scaling system comprises that the temperature controller (4) that is positioned at constant temperature oven (2) outside is used for controlling the temperature of constant temperature oven (5), thereby changes calibration LED (6) environment temperature.It is upper that calibration LED (6) is fixed on support (7), and be connected with pulsed constant current supply (8).Light-conductive optic fibre (9) collection that the light that calibration LED (6) sends is put in constant temperature oven (5) enters the high precision spectrometer (2) that is connected to computing machine (3).Measuring system comprises white LED light source to be measured (1) and computing machine (3).The spectrometer (2) of specially surveying the blue light wavelength displacement consists of spherical mirror (10), entrance slit (11), plane grating (12), exit slit (13), CCD (14) and driving circuit (15).
Adopt technique scheme, its characteristics are:
While 1, calibrating, by the calibration LED that makes off-position, in constant temperature oven, place 30min and guarantee that this LED equates with environment temperature in the junction temperature of the moment of switching on, avoided measuring virtual junction temperature with additive method, reduced error.
2, with the constant temperature oven of temperature controller, be used to provide the environment temperature of calibration LED, error is no more than 1 ℃.And can change environment temperature and the junction temperature of calibration LED, carry out many group experiments, improve the accuracy of LED peak wavelength-junction temperature COEFFICIENT K.
3, pulsed constant current supply can provide instantaneous working current for calibration LED, and it is worked at short notice, makes and is calibrating out the peak wavelength of LED under specified temp, does not cause the variation of junction temperature simultaneously.
4, LED support can conveniently be fixed calibration LED, stablizes its metering circuit, and the vibration reduced due to device brings error to experiment.
5, light-conductive optic fibre one end stretches into constant temperature oven, and the other end is connected with spectrometer.The light that LED to be measured sends is faster, loss is transferred in spectrometer as small as possible.
6, this spectrometer wavelength measurement range of specially surveying blue light wavelength displacement is 440nm～470nm, is greater than the moving range of white light LEDs causes when junction temperature changes peak wavelength.And the exact value while greatly having improved spectral measurement, degree of accuracy is better than 0.02nm.
7, this device can be to the peak wavelength of large power white light LED-junction temperature COEFFICIENT K, initial junction temperature T
aAnd initial wavelength X
aCalibrate, pass through computer stored.For the junction temperature measurement of white light LEDs provides data.
While 8, measuring, just can calculate fast junction temperature as long as under running current, record the luminescent spectrum of this LED.No matter during measure spectrum, can directly under the LED working environment, measure, without the dismounting light fixture, be single led or integrated optical source can fast and easy be measured, and application is extensive.
9, the spectrometer of specially surveying the blue light wavelength displacement, by the design to optical splitter, makes the light level that LED to be measured sends enter in optical splitter, through the plane grating that enters of catoptron.The light gone out by optical grating diffraction is through the reflection of catoptron, only have wavelength coverage to pass in the luminous energy level of 440nm～470nm the exit slit that length is d, shine and have on the CCD of photosurface that width is d, through overdrive circuit sampling and opto-electronic conversion, finally obtain on computers the high-precision curve of spectrum.
The accompanying drawing explanation
Fig. 1 shows apparatus of the present invention scaling system and forms schematic diagram
Fig. 2 shows apparatus of the present invention measuring system and forms schematic diagram
Fig. 3 shows the structural representation of special survey blue light wavelength displacement spectrometer of the present invention
Fig. 4 shows the peak wavelength of different model LED in the present invention-junction temperature coefficients statistics table
Embodiment
The present invention utilizes a kind of quick non-cpntact measurement white light LEDs junction temperature device of peak wavelength displacement method design.This device comprise the spectrometer of special survey blue light wavelength displacement design, the peak wavelength of white light LEDs commonly used-junction temperature COEFFICIENT K is calibrated and the LED under normal operating conditions is carried out to junction temperature measurement.
The spectrometer of special survey blue light wavelength displacement of the present invention is to control diffracted ray by parameter and the angle of determining plane grating, makes diffracted ray after reflection only have wavelength just can pass through exit slit in 440nm～470nm scope.It is 2048 line array CCD that the present embodiment is chosen the pixel element, and the height of this CCD photosurface and the width of exit slit equate.The light signal of detector gained is converted into to electric signal, and processes by the signal of driving circuit, finally demonstrate on computers the spectrum of detection LED.By the spectrum that this device records, wavelength coverage is 440nm～470nm, and precision is 0.015nm.
During calibration, calibration LED is arranged on LED support, by temperature controller, constant temperature oven is carried out to temperature control, and 10 ℃ of 5 groups of experimental group, 30 ℃, 50 ℃, 70 ℃, 90 ℃ are set.
T
1In the time of=10 ℃, make to calibrate LED and put half an hour the constant temperature oven interruption tele-release of 10 ℃, can think that now the junction temperature of this calibration LED is 10 ℃.Then by pulsed constant current supply, give the momentary current I that mono-of LED of calibration equates with working current, the time is 5s, by the detection of spectrometer, can obtain on computers the curve of spectrum of calibration LED when normal operation, thereby obtain at this calibration LED junction temperature T
J1Peak wavelength λ in the time of=10 ℃
1.
Repeat said process and can obtain 5 groups of junction temperatures and corresponding peak wavelength.T
j1～λ
1、T
j2～λ
2、T
j3～λ
3、T
j4～λ
4、T
j5～λ
5。In conjunction with the peak wavelength method, measure the formula of junction temperature
Combination of two is obtained 10 K values, then averages.Can obtain the peak wavelength of this calibration LED-junction temperature COEFFICIENT K, initial junction temperature T
aAnd initial spike wavelength X
a, record data.
The white light LEDs of commonly using on the market model is calibrated according to the method described above, by the data obtained K, T
a, λ
aBe organized into form, namely completed calibration.
During measurement, no matter be single led or integrated optical source, under LED normal operating conditions to be measured, the luminescent spectrum while recording its stabilized illumination, obtain the peak wavelength λ of LED to be measured under this duty by computing machine.Inquiry peak wavelength-junction temperature coefficients statistics table can obtain the peak wavelength of this model LED-junction temperature COEFFICIENT K, initial junction temperature T
aAnd initial wavelength X
a, by data substitution formula
Can obtain fast the junction temperature of LED to be measured under this duty.
Because the spectrometer of this device is specially surveyed the blue light wavelength displacement, its spectral accuracy can reach 0.015nm, and the junction temperature precision of namely calculating is 0.1 ℃.Meet designing requirement.
Claims (8)
1. one kind is utilized peak wavelength displacement method, quick non-cpntact measurement white light LEDs junction temperature device, structure comprises measuring system and scaling system, and measuring system comprises white LED light source to be measured (1), specially surveys spectrometer (2) and the computing machine (3) of blue light wavelength displacement; Scaling system comprises temperature controller (4), constant temperature oven (5), calibration LED (6), LED lamp support (7), pulsed constant current supply (8), spectrometer (2) and computing machine (3).It is characterized in that: non-contact type is measured junction temperature, and convenient and swift, precision is high.The designed spectrometer wavelength measurement range of this device is 440nm～470nm, and precision is better than 0.02nm.
2. a kind of quick non-cpntact measurement white light LEDs junction temperature device according to claim 1 is characterized in that: to the peak wavelength of large power white light LED-junction temperature COEFFICIENT K, initial junction temperature T
aAnd initial spike wavelength X
aCalibrate, for the junction temperature measurement of white light LEDs provides data, make junction temperature measurement easier, quick.
3. a kind of quick non-cpntact measurement white light LEDs junction temperature device according to claim 1, it is characterized in that: during calibration, by the calibration LED that makes off-position, in constant temperature oven, place 30min and guarantee that this LED equates with environment temperature in the junction temperature of the moment of switching on, has reduced error.
4. a kind of quick non-cpntact measurement white light LEDs junction temperature device according to claim 1, it is characterized in that: during calibration, the instantaneity of the working current that provides of calibration LED is provided pulsed constant current supply, makes the temperature rise of calibration LED within conduction time very little, can ignore.
5. a kind of quick non-cpntact measurement white light LEDs junction temperature device according to claim 1 is characterized in that: during calibration, the light-conductive optic fibre by stretching into constant temperature oven can be more fast, loss more is transmitted to spectroanalysis instrument by the light that tested LED sends in lowland.The response time of spectrometer and the conduction time of calibration LED have been shortened.
6. a kind of quick non-cpntact measurement white light LEDs junction temperature device according to claim 1 is characterized in that: during measurement directly under the LED duty, record the peak wavelength under this state by spectrometer, in conjunction with formula
Can calculate fast the junction temperature of this LED under this duty, easy and simple to handle, can be widely used in single led or integrated optical source.Gained junction temperature degree of accuracy can reach 0.1 ℃.
7. a kind of quick non-cpntact measurement white light LEDs junction temperature device according to claim 1, it is characterized in that: the wavelength measurement scope that this system special secondary school is surveyed the spectrometer of blue light wavelength displacement is 440nm～470nm, be greater than the moving range of white light LEDs causes when junction temperature changes peak wavelength, the peak wavelength measuring accuracy is better than 0.02nm.
8. a kind of quick non-cpntact measurement white light LEDs junction temperature device according to claim 1, it is characterized in that: the spectrometer of specially surveying blue light wavelength displacement is the optical design that utilizes catoptron and plane grating, makes the light of wavelength in 440nm～470nm just shine on the CCD of photosurface that width is d.
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Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103995223A (en) * | 2014-04-11 | 2014-08-20 | 清华大学深圳研究生院 | Method and apparatus for measuring thermal characteristic of LED |
| CN105044583A (en) * | 2015-06-05 | 2015-11-11 | 江苏理工学院 | Test apparatus for LED junction temperature K coefficient |
| CN106052898A (en) * | 2016-08-09 | 2016-10-26 | 上海禾赛光电科技有限公司 | Wireless temperature measuring device based on spectrum technology and method thereof |
| CN107741411A (en) * | 2017-10-13 | 2018-02-27 | 中国科学院上海技术物理研究所 | A kind of isometric helix multiple spot ultraviolet spectra freezes serum analysis instrument |
| CN108680849A (en) * | 2018-07-06 | 2018-10-19 | 中国电子技术标准化研究院 | A kind of measurement method and device of electronic device junction temperature |
| CN109405995A (en) * | 2018-09-17 | 2019-03-01 | 中国电子科技集团公司第五十五研究所 | A kind of analysis method improving the junction temperature of chip measuring accuracy based on Raman spectroscopy |
| CN109596963A (en) * | 2018-12-18 | 2019-04-09 | 中国电子科技集团公司第十三研究所 | It is a kind of for detecting the impulse modulation device of junction temperature |
| CN110793670A (en) * | 2019-11-14 | 2020-02-14 | 深圳大学 | Method and device for measuring junction temperature of white light LED |
| CN111982340A (en) * | 2020-08-28 | 2020-11-24 | 常州工学院 | Non-contact LED junction temperature measuring method and device |
| CN113281008A (en) * | 2021-03-31 | 2021-08-20 | 昂纳信息技术（深圳）有限公司 | Chip welding state detection method for optical device |
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Cited By (15)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103995223A (en) * | 2014-04-11 | 2014-08-20 | 清华大学深圳研究生院 | Method and apparatus for measuring thermal characteristic of LED |
| CN103995223B (en) * | 2014-04-11 | 2016-08-17 | 清华大学深圳研究生院 | A kind of method measuring light emitting diode thermal characteristics and device thereof |
| CN105044583A (en) * | 2015-06-05 | 2015-11-11 | 江苏理工学院 | Test apparatus for LED junction temperature K coefficient |
| CN106052898A (en) * | 2016-08-09 | 2016-10-26 | 上海禾赛光电科技有限公司 | Wireless temperature measuring device based on spectrum technology and method thereof |
| CN106052898B (en) * | 2016-08-09 | 2018-08-31 | 上海禾赛光电科技有限公司 | Wireless temperature measuring device based on spectral technique and method |
| CN107741411A (en) * | 2017-10-13 | 2018-02-27 | 中国科学院上海技术物理研究所 | A kind of isometric helix multiple spot ultraviolet spectra freezes serum analysis instrument |
| CN108680849A (en) * | 2018-07-06 | 2018-10-19 | 中国电子技术标准化研究院 | A kind of measurement method and device of electronic device junction temperature |
| CN108680849B (en) * | 2018-07-06 | 2024-03-22 | 中国电子技术标准化研究院 | Method and device for measuring junction temperature of electronic device |
| CN109405995A (en) * | 2018-09-17 | 2019-03-01 | 中国电子科技集团公司第五十五研究所 | A kind of analysis method improving the junction temperature of chip measuring accuracy based on Raman spectroscopy |
| CN109596963A (en) * | 2018-12-18 | 2019-04-09 | 中国电子科技集团公司第十三研究所 | It is a kind of for detecting the impulse modulation device of junction temperature |
| CN109596963B (en) * | 2018-12-18 | 2021-09-21 | 中国电子科技集团公司第十三研究所 | Pulse modulation device for detecting junction temperature |
| CN110793670A (en) * | 2019-11-14 | 2020-02-14 | 深圳大学 | Method and device for measuring junction temperature of white light LED |
| CN111982340A (en) * | 2020-08-28 | 2020-11-24 | 常州工学院 | Non-contact LED junction temperature measuring method and device |
| CN111982340B (en) * | 2020-08-28 | 2022-03-08 | 常州工学院 | Non-contact LED junction temperature measuring method and device |
| CN113281008A (en) * | 2021-03-31 | 2021-08-20 | 昂纳信息技术（深圳）有限公司 | Chip welding state detection method for optical device |
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