CN103411702B - The device of method non-cpntact measurement junction temperature of white LED is shifted using peak wavelength - Google Patents
The device of method non-cpntact measurement junction temperature of white LED is shifted using peak wavelength Download PDFInfo
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Abstract
The present invention discloses one kind using peak wavelength displacement method, fast speed non-contact measurement junction temperature of white LED device, including measuring system and scaling system, measuring system includes white LED light source to be measured (1), specially surveys the spectrometer (2) and computer (3) of blue light wavelength displacement；Spectrometer is made up of spherical mirror (10), entrance slit (11), plane grating (12), exit slit (13), CCD (14) and drive circuit (15), it is characterized in that wavelength measurement scope is 440nm~470nm, accuracy is better than 0.02nm.Scaling system includes temperature controller (4), insulating box (5), calibration LED (6), LED lamp holder (7), pulsed constant current supply (8), spectrometer (2) and computer (3).Demarcated by the peak wavelength junction temperature COEFFICIENT K to large power white light LED, the shift amount of peak wavelength, obtains the junction temperature under LED white light sources working condition to be measured, gained junction temperature accuracy is up to 0.1 DEG C during measurement LED real works.
Description
Technical field
The present invention relates to junction temperature inside semiconductor light-emitting-diode (LED) detection technique, more particularly to a kind of LED chip
Measuring instrument.
Background technology
High-brightness LED has an epoch-marking significance, and it will be that the mankind are most big after Edison invented incandescent lamp bulb
One of big invention, is referred to as forth generation lighting source or green light source, and compared with conventional light source, it has lot of advantages：Light
The features such as imitating height, mercury-free environmental protection, long lifespan, small volume, has been widely used for various instructions, display, decoration, backlight, city
The special lighting such as city's night scene field.Current LED luminance is only capable of reaching 10%-30%, while the energy for having 70%-90% turns
Heat energy is changed into.The raising of high-performance white light LEDs optical property and reliability, all relies on the junction temperature of chip.Therefore how to supervise
Control junction temperature, especially online lossless junction temperature monitoring, be just possibly realized the application of restriction white light LEDs and it is anxious to be resolved the problem of.
LED basic structure is the P-N junction of a semiconductor.When electric current flows through LED element, the temperature of P-N junction will be upper
Rise, said on stricti jurise, the junction temperature that the temperature in P-N junction area is just defined as LED is typically due to element chip and is respectively provided with very little
Size, therefore the temperature of LED chip can also be regarded it as junction temperature by not strict place sometimes.The chip sizes of white light LEDs is small, electricity
Current density is big, so caused temperature rise is obvious.And do not include infrared part in its luminescent spectrum, so what device was produced
Heat cannot rely on heat radiation and discharge, and inputs 70-90% of electric energy or so and is transformed into heat, these heats are most of all
Being converted into makes the elevated energy of chip self-temperature.For semiconductor devices, the change of temperature, its characteristic has obvious change
Change.Particularly great power LED, this influence will be apparent from, and chip temperature directly influences LED luminous efficiency, dominant wavelength
And service life.There is data to show, about 70% LED product failure is too high from junction temperature.And it is specified work(in load
Temperature often raises 20 DEG C of failures and just rises one times in the case of rate half.Therefore the junction temperature for how rapidly and accurately measuring LED can
To help us more reasonably to carry out LED structure design and optimization LED illumination engineering heat dissipation design.
At present, the method for measurement junction temperature of white LED mainly has：1st, forward voltage method, using the electric delivery temperature effects of LED,
Under the condition of constant current, the linear relationship of forward voltage and junction temperature is obtained；2nd, pin method, using in LED luminescent spectrum
The power ratio of blue light and white light is measured.These methods belong to contact type measurement, and the junction temperature for being confined to single tube LED component is surveyed
Amount.Also there is researcher to propose some contactless junction temperature measurement methods now：Blue Bai Bifa, infrared photography method and peak wavelength
Method.Because the use of these methods is limited in scope, and ratio of precision is relatively low.Peak wavelength method, utilizes the peak of LED luminescent spectrum
Value can increase with the rise of junction temperature.But because peak wavelength caused by junction temperature rise drifts about and little, when raising 10 DEG C,
Peak wavelength changes about 1.4nm or so, and no small error must be so brought to test result, according to conventional high-precision light
Spectrometer, then can greatly increase testing cost.
Accordingly, it would be desirable to a kind of contactless, high accuracy, low cost are designed, and junction temperature of white LED measurement simple to operation
Instrument.
The content of the invention
In view of the deficiency of the above method and technology, the purpose of type of the present invention is to utilize a kind of tool of peak wavelength displacement method design
There is large power white light LED junction temperature measurement device high-precision, inexpensive, easy to operate.
In order to realize the purpose of type of the present invention, intend using following technology：
A kind of fast speed non-contact measures junction temperature of white LED measurement apparatus, it is characterised in that：The system is by calibrating and measuring two
Part is constituted, during calibration, and calibration LED (6) is arranged in insulating box (5), and will calibrate LED (6) with a light-conductive optic fibre (9) sends
Light be transmitted to specially survey blue light wavelength displacement spectroanalysis instrument (2).Obtained by the computer (3) being connected on spectrometer (2)
To peak wavelength at this temperature, and obtain by multi-group data the calibration LED peak wavelength-junction temperature COEFFICIENT K, initial junction temperature
TaAnd initial spike wavelength Xa.During measurement, by spectrometer (2) direct measurement LED to be measured (1) in normal operation
Peak wavelength, with reference to formulaQuickly calculate the junction temperature of LED to be measured under the working condition.
The temperature controller (4) that scaling system includes being located on the outside of insulating box (2) is used for controlling the temperature of insulating box (5),
So as to change calibration LED (6) environment temperature.Calibration LED (6) is fixed on support (7), and is connected with pulsed constant current supply (8)
Connect.The light-conductive optic fibre (9) that the light that calibration LED (6) is sent is put in insulating box (5) collects the height for entering and being connected to computer (3)
Precision spectrometer (2).Measuring system includes white LED light source to be measured (1) and computer (3).Specially survey the light of blue light wavelength displacement
Spectrometer (2) is by spherical mirror (10), entrance slit (11), plane grating (12), exit slit (13), CCD (14) and drives
Dynamic circuit (15) is constituted.
Using above-mentioned technical proposal, its feature is：
When the 1st, calibrating, ensure the LED in energization by making the calibration LED of off-position place 30min in insulating box
The junction temperature of moment is equal with environment temperature, it is to avoid with other method measure virtual junction temperature, reduces error.
2nd, the insulating box with temperature controller is used for providing calibration LED environment temperature, and error is no more than 1 DEG C.And
Calibration LED environment temperature and junction temperature can be changed, multigroup experiment is carried out, the accurate of LED peak wavelengths-junction temperature COEFFICIENT K is improved
Property.
3rd, pulsed constant current supply can provide instantaneous operating current for calibration LED, make its normal work in a short time, make
Obtain and calibrating out the peak wavelengths of LED at a certain temperature, while not causing the change of junction temperature.
4th, LED support conveniently fixed can calibrate LED, stablize its measuring circuit, reduce the vibration due to device to experiment
Bring error.
5th, insulating box is stretched into light-conductive optic fibre one end, and the other end is connected with spectrometer.The light that LED to be measured is sent is more
It hurry up, be lost and be transferred to as small as possible in spectrometer.
6th, the spectrometer wavelength measurement range for specially surveying blue light wavelength displacement is 440nm~470nm, is existed more than white light LEDs
The moving range of junction temperature peak wavelength caused when changing.And substantially increase exact value during spectral measurement, accuracy
Better than 0.02nm.
7th, the device can be to large power white light LED peak wavelength-junction temperature COEFFICIENT K, initial junction temperature TaAnd initial wavelength λa
Calibrated, pass through computer stored.Data are provided for the junction temperature measurement of white light LEDs.
When the 8th, measuring, junction temperature just can be quickly calculated as long as measuring the luminescent spectrum of the LED under running current.Survey
It can be measured during amount spectrum directly under LED operation environment, without dismantling light fixture, either single led or integrated optical source is all
It can be measured with fast and easy, application field is extensive.
9th, the spectrometer for specially surveying blue light wavelength displacement passes through the design to optical splitter so that the light level that LED to be measured is sent
Into in optical splitter, by the entrance plane grating of speculum.The light gone out by optical grating diffraction passes through the reflection of speculum, only
Wave-length coverage 440nm~470nm luminous energy horizontal through the exit slit that length is d, be irradiated to photosensitive for d with width
On the CCD in face, through overdrive circuit sampling and opto-electronic conversion, the high-precision curve of spectrum is finally obtained on computers.
Brief description of the drawings
Fig. 1 shows apparatus of the present invention scaling system composition schematic diagram
Fig. 2 shows apparatus of the present invention measuring system composition schematic diagram
Fig. 3 shows that the special survey blue light wavelength of the present invention shifts the structural representation of spectrometer
Fig. 4 shows peak wavelength-junction temperature coefficients statistics table of different model LED in the present invention
Embodiment
The present invention is to design a kind of fast speed non-contact measurement junction temperature of white LED device using peak wavelength displacement method.The dress
Put the design of the spectrometer including specially surveying blue light wavelength displacement, the peak wavelength-junction temperature COEFFICIENT K for commonly using white light LEDs is determined
Mark and junction temperature measurement is carried out to the LED under normal operating conditions.
The spectrometer of the special survey blue light wavelength displacement of the present invention is controlled by determining the parameter and angle of plane grating
Diffracted ray processed so that diffracted ray after reflection only has wavelength just can be narrow by outgoing in the range of 440nm~470nm
Seam.The present embodiment chooses the line array CCD that pixel element is 2048, and the height of the CCD photosurfaces and the width of exit slit are equal.Will
Optical signal obtained by detector is converted into electric signal, and by the signal transacting of drive circuit, finally shows on computers
Detected LED spectrum.The spectrum measured by the present apparatus, wave-length coverage is 440nm~470nm, and precision is 0.015nm.
During calibration, calibration LED is arranged on LED support, is carried out temperature control to insulating box by temperature controller, is set 5 groups
10 DEG C, 30 DEG C, 50 DEG C, 70 DEG C, 90 DEG C of experimental group.
T1At=10 DEG C, calibration LED is set to be electrically disposed half an hour in 10 DEG C of insulating box interruption, then it is believed that the now calibration
LED junction temperature is 10 DEG C.Then by pulsed constant current supply, to calibration, LED mono- is equal with operating current, the time is the instantaneous of 5s
Electric current I, by the detection of spectrometer, can obtain the curves of spectrum of the calibration LED in normal work on computers, so that
To in calibration LED junction temperature Tj1Peak wavelength λ at=10 DEG C1。
It is that can obtain 5 groups of junction temperatures and corresponding peak wavelength to repeat said process.Tj1~λ1、Tj2~λ2、Tj3~λ3、Tj4
~λ4、Tj5~λ5.The formula of junction temperature is measured with reference to peak wavelength methodCombination of two obtains 10 K values, then is averaged
Value.Calibration LED peak wavelength-junction temperature COEFFICIENT K, initial junction temperature T can be obtainedaAnd initial spike wavelength Xa, record number
According to.
The white light LEDs for commonly using model on the market are calibrated according to the method described above, by the data obtained K, Ta、λaIt is organized into
Form, that is, complete calibration.
During measurement, whether single led or integrated optical source under LED normal operating conditions to be measured, measures its stable hair
The luminescent spectrum of light time, peak wavelength λs of the LED to be measured under the working condition is obtained by computer.Inquire about peak wavelength-knot
Warm coefficients statistics table can obtain model LED peak wavelength-junction temperature COEFFICIENT K, initial junction temperature TaAnd initial wavelength λa, by number
According to substitution formulaJunction temperatures of the LED to be measured under the working condition can quickly be obtained.
Because the spectrometer of the device specially surveys blue light wavelength displacement, its spectral accuracy is up to 0.015nm, that is, the knot calculated
Warm precision is 0.1 DEG C.Meet design requirement.
Claims (6)
1. one kind is using peak wavelength displacement method fast speed non-contact measurement junction temperature of white LED device, structure include measuring system and
Scaling system, measuring system includes white LED light source to be measured (1), specially surveys the spectrometer (2) and computer of blue light wavelength displacement
(3)；Scaling system includes temperature controller (4), insulating box (5), calibration LED (6), LED lamp holder (7), pulsed constant current supply
(8) spectrometer (2) and computer (3) of blue light wavelength displacement, the work that the pulsed constant current supply is provided for calibration LED, are specially surveyed
Make the instantaneity of electric current so that temperature rise very littles of the calibration LED within conduction time, can ignore, the special survey blue light wavelength is moved
The spectrometer of position passes through the design to optical splitter so that measures the light level that LED sends and enters optical splitter, enters by speculum
Plane grating, the light gone out by optical grating diffraction passes through the reflection of speculum, only luminous energy of the wave-length coverage in 440nm~470nm
Horizontal through length be d exit slit, be irradiated to width for d photosurface CCD on, through overdrive circuit sampling and
Opto-electronic conversion, finally obtains the high-precision curve of spectrum, non-contact type measures junction temperature, convenient and swift, and precision is high on computers,
Spectrometer wavelength measurement range designed by the device is 440nm~470nm, and precision is better than 0.02nm, during calibration, by making to break
The calibration LED of electricity condition places 30min to ensure that the LED is equal with environment temperature in the junction temperature for the moment that is powered in insulating box,
Reduce error.
2. it is according to claim 1 a kind of using peak wavelength displacement method fast speed non-contact measurement junction temperature of white LED device,
It is characterized in that：Peak wavelength-junction temperature COEFFICIENT K, initial junction temperature T to large power white light LEDaAnd initial spike wavelength XaEnter
Row calibration, provides data so that junction temperature measurement is easier, quick for the junction temperature measurement of white light LEDs.
3. it is according to claim 1 a kind of using peak wavelength displacement method fast speed non-contact measurement junction temperature of white LED device,
It is characterized in that：During calibration, by stretch into insulating box light-conductive optic fibre can more rapidly, loss tested LED is sent lower
Light be transmitted to spectroanalysis instrument, shorten spectrometer response time and calibration LED conduction time.
4. it is according to claim 1 a kind of using peak wavelength displacement method fast speed non-contact measurement junction temperature of white LED device,
It is characterized in that：The peak wavelength under the state is directly measured by spectrometer under LED operation state during measurement, with reference to formulaJunction temperatures of the LED under the working condition can be quickly calculated, it is easy to operate, list can be widely used in
Individual LED or integrated optical source, gained junction temperature accuracy up to 0.1 DEG C, wherein, TjFor LED to be measured junction temperatures in the operating condition, K
To calibrate LED peak wavelength-junction temperature coefficient, TaFor initial junction temperature, λaIt is LED in normal work shape for initial spike wavelength, λ
Peak wavelength under state.
5. it is according to claim 1 a kind of using peak wavelength displacement method fast speed non-contact measurement junction temperature of white LED device,
It is characterized in that：The wavelength measurement scope for specially surveying the spectrometer of blue light wavelength displacement is 440nm~470nm, is existed more than white light LEDs
The moving range of junction temperature peak wavelength caused when changing, peak wavelength measurement accuracy is better than 0.02nm.
6. it is according to claim 1 a kind of using peak wavelength displacement method fast speed non-contact measurement junction temperature of white LED device,
It is characterized in that：The spectrometer for specially surveying blue light wavelength displacement is the optical design using speculum and plane grating so that wavelength
Light in 440nm~470nm is just irradiated on the CCD for the photosurface that width is d.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| 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 |
| CN109141669B (en) * | 2016-08-09 | 2020-08-07 | 上海禾赛光电科技有限公司 | Wireless temperature measurement method and device based on spectrum technology |
| CN107741411B (en) * | 2017-10-13 | 2020-01-10 | 中国科学院上海技术物理研究所 | Cryopreservation serum analyzer for equidistant spiral multipoint ultraviolet spectrum |
| 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 |
| 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 |
| 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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| CN201212842Y (en) * | 2008-04-11 | 2009-03-25 | 中国科学院广州电子技术研究所 | Large power LED junction temperature measurement device |
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