CN203869783U - Low-cost high-precision LED node temperature measuring instrument - Google Patents
Low-cost high-precision LED node temperature measuring instrument Download PDFInfo
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- CN203869783U CN203869783U CN201420151595.6U CN201420151595U CN203869783U CN 203869783 U CN203869783 U CN 203869783U CN 201420151595 U CN201420151595 U CN 201420151595U CN 203869783 U CN203869783 U CN 203869783U
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Abstract
The utility model provides a low-cost high-precision LED node temperature measuring instrument. The low-cost high-precision LED node temperature measuring instrument comprises a forward pressure drop detection unit, a data obtaining device, a mercury switch and an LED driver. The LED driver is a constant current source, the data obtaining device can be electrically connected with the forward pressure drop detection unit, and the mercury switch can switch an LED node to be measured to an equivalent load from the LED driver during a measuring process and switch the LED node to the LED driver from the equivalent load.
Description
Technical field
The utility model relates to a kind of LED junction temperature surveying instrument, particularly relates to a kind of low cost, the LED junction temperature surveying instrument of pinpoint accuracy.
Background technology
The patent No. is 8,278,831; 7,758,240; 7,052,180; 5,401,099 United States Patent (USP) has been described respectively the different modes of measuring semiconductor node temperature, and all these instruments also can be for measuring LED junction temperature.But all these surveying instruments all exist a drawback to be exactly, it can only be applicable to laboratory environment and simple junction temperature is measured.In these patents, measured being is simple, small and exquisite device, and the connection between these measured devices and surveying instrument are all brief, therefore, have very little stray capacitance, leakage inductance and less noise.Yet when the junction temperature of reality test LED, measured device may be very complicated and huge, it has large many stray capacitances in system, leakage inductance, and in addition, the noise of factory also will be more much bigger than laboratory.Given this, the method described in above-mentioned patent is unsuitable for the practical operation of LED junction temperature test, and the environment of plant.
Utility model content
An object of the present utility model is to provide a kind of LED junction temperature surveying instrument, and it can be used in the environment of plant that noise is very large.
Another object of the present utility model is to provide a kind of LED junction temperature surveying instrument, and it can measure single LED or many LED(COB) or there is the LED of stationary installation.
Another object of the present utility model is to provide a kind of LED junction temperature surveying instrument, and it can self-verification.
Another object of the present utility model is to provide a kind of LED junction temperature surveying instrument, and it can be in very rear duplicate measurements of short wait time (<10s).
Other advantage of the present utility model and feature are fully demonstrated by following detailed description and can be achieved by the means specially pointed out in claims and the combination of device.
According to the utility model, the utility model LED junction temperature surveying instrument that can realize aforementioned object and other objects and advantage comprises:
An electric power supply apparatus,
A constant current source with high precision and high stability, can be connected in this electric power supply apparatus and this tested LED, the steady current of this constant current source is less than 10% of this tested LED working current, wherein, this steady current has a variable clamp voltage from several volts to several hectovolts
An equivalent load, during measuring, is connected in this steady current,
A mercury cut-off 30(SW), this switch (SW) can switch this steady current between LED and equivalent load, is less than 20ms switching time,
One for receiving the data acquisition facility of data,
A data transmission interface, the accessible computing machine of this data transmission interface is to control and to process the data that this data processing equipment gets.
The utility model further provides a kind of LED junction temperature surveying instrument, comprising:
One forward voltage drop detecting unit;
One data acquisition facility;
One mercury cut-off; With
One LED drives, and wherein this LED drives as constant current source, and wherein this data acquisition facility can be switched on and is connected with this voltage drop detection unit; Wherein this mercury cut-off can drive LED node to be measured to switch to an equivalent load from LED in measuring process, and after completing measurement, this LED node is driven to this LED from this equivalence load switching.
The utility model further provides a kind of LED junction temperature measuring method, comprises the following steps:
(A) connect a LED and be urged to a LED node to be measured, wherein this LED drives as constant current source;
(B) wait for the electric current stable output driving to this LED, start a data acquisition facility and by a mercury cut-off, LED node to be measured driven and switches to an equivalent load from LED;
(C), after data acquisition finishes, by this mercury cut-off, LED node to be measured is driven and switches to this equivalent load from LED.
By the understanding of the description to subsequently and accompanying drawing, the further object of the utility model and advantage will be fully demonstrated.
These and other objects of the present utility model, characteristics and advantages, by following detailed description, accompanying drawing and claim are fully demonstrated.
Accompanying drawing explanation
Fig. 1 is the circuit diagram according to the LED junction temperature surveying instrument of the utility model preferred embodiment, and this figure has explained this LED junction temperature surveying instrument and measured for the junction temperature of the LED group of one group of LED knot composition.
Fig. 2 is the circuit diagram according to the LED junction temperature surveying instrument of the utility model preferred embodiment, and this figure has explained this LED junction temperature surveying instrument and measured for the junction temperature of LED fixed equipment or COB.
Fig. 3 is the circuit diagram according to the LED junction temperature surveying instrument of the utility model preferred embodiment, and this figure has explained this LED junction temperature surveying instrument and measured for the junction temperature of single led knot.
Fig. 4 is the performance of handoffs schematic diagram of mechanical relay and electronic relay.
Fig. 5 is the performance of handoffs schematic diagram according to the mercury cut-off of the LED junction temperature surveying instrument of the utility model preferred embodiment.
Fig. 6 is a schematic diagram, has shown the LED electric current while there is no equivalent load.
Fig. 7 is a schematic diagram, has shown the LED electric current while having an equivalent load.
Fig. 8 is a schematic diagram, has shown the set of time between switch and current source.
Fig. 9 is a schematic diagram, has shown how when there is no rapid data acquisition device, to improve data accuracy.
Embodiment
Following description is disclosed so that those skilled in the art can manufacture and use the utility model.The preferred embodiment providing in following description is only as example and the modification that it will be apparent to those skilled in the art, and it does not form the restriction to the utility model scope.In following description defined General Principle can not deviate from the utility model spirit and utility model scope and be applied to other embodiment, optional substitute, revise, be equal to implement and apply.
Fig. 1 to Fig. 9 with reference to the utility model accompanying drawing, LED junction temperature surveying instrument according to the utility model preferred embodiment is illustrated, wherein this LED junction temperature surveying instrument comprises that a forward voltage drop detecting unit 10, a data acquisition facility 20, a mercury cut-off 30 and a LED drive 60, wherein this LED drives 60 to be constant current source, and wherein this data acquisition facility 20 can be switched on and is connected with this voltage drop detection unit 10; Wherein this mercury cut-off 30 can drive 60 to switch to an equivalent load 50 from LED by LED node to be measured (or one group of LED node group or LED equipment or COB that LED node forms) in measuring process, and after completing measurement, this LED node is switched to this LED driving 60 from this equivalent load 50.Preferably, be less than 20ms the switching time of this mercury cut-off 20.
As shown in Fig. 3 of Fig. 1 of accompanying drawing, according to the LED junction temperature surveying instrument of the utility model preferred embodiment, can provide an equivalent load 50, wherein this equivalent load 50 is connected in this LED and drives 60 during measuring.
As shown in Fig. 3 of Fig. 1 of accompanying drawing, LED junction temperature surveying instrument according to the utility model preferred embodiment further comprises an electric power supply apparatus 40, wherein this electric power supply apparatus 40 can be switched on and is connected with this data acquisition facility 20 with this mercury cut-off 30 respectively, and can provide electric energy with this data acquisition facility 20 for this mercury cut-off 30.
As shown in Fig. 3 of Fig. 1 of accompanying drawing, LED junction temperature surveying instrument according to the utility model preferred embodiment further comprises a data transmission interface 70, wherein this data transmission interface 70 can be connected with this data acquisition facility 20 with switching on, and the data in this data acquisition facility 20 can be downloaded by this data transmission interface 70
LED junction temperature surveying instrument according to the utility model preferred embodiment further comprises that a thermal coupling thermometer is for measuring room temperature, and this thermal coupling thermometer can be switched on and is connected with this electric power supply apparatus 40 with this data acquisition facility 20 respectively.
It should be noted that this LED drives 60 only to have two ports to switch on to be connected in this forward voltage drop detecting unit 10, and other port physically driven 60 to disconnect with this LED by relay, or blocked by photoelectrical coupler.
The utility model also further provides a kind of LED junction temperature measuring method, and it comprises the following steps:
(A) connect a LED and be urged to a LED node to be measured, wherein this LED drives as constant current source;
(B) wait for the electric current stable output driving to this LED, start a data acquisition facility and by a mercury cut-off, LED node to be measured driven and switches to an equivalent load from LED;
(C), after data acquisition finishes, by this mercury cut-off, LED node to be measured is driven and switches to this equivalent load from LED.
Preferably, this LED junction temperature measuring method further comprises a self-checking step, and wherein this self-checking step in above-mentioned steps (A) before and comprise the steps:
1) at room temperature, connect LED node to be measured LED junction temperature surveying instrument;
2), after environment temperature is stable, open data acquisition facility to measure first data point with inner constant current source;
3) move in tested LED node to baking box, adjust the temperature of this baking box extremely higher than 50 ℃ of room temperatures;
4) according to step 2 to obtain the second data point;
5) use the first data and the second data point to make a self-checking K line chart.
Preferably, this LED junction temperature measuring method further comprises a self-checking step, and wherein this self-checking step in above-mentioned steps (A) before and comprise the steps:
1) at room temperature, by LED node to LED junction temperature surveying instrument;
2), after temperature stabilization, open data acquisition facility to obtain the first data point;
3) move in this LED node to baking box, adjust the temperature of this baking box extremely higher than 50 ℃ of room temperatures;
4) according to step 2, obtain the 2nd LED forward voltage;
5) use the first data and the second data point to make a self-checking K line chart.As shown in Fig. 1 of accompanying drawing, the measurement that can be used in the LED node group that a plurality of LED nodes form according to the LED junction temperature surveying instrument of the utility model preferred embodiment wherein this LED junction temperature surveying instrument has a high precision, the constant current source of high stability drives 60 as LED, this constant current source and power lead and control line disconnect completely, one without revealing, ripple disable and the mercury cut-off 30(SW that can switch fast) 30, a data acquisition facility 20, an equivalent load 50, a thermal coupling thermometer is (optional, be not presented in block diagram), a data transmission interface 70, with an electric power supply apparatus 40 as power source.According to the figure, also comprise a data processing equipment 80, as a computing machine that is applicable to data processing is used to control and data processing.
Wherein, the constant current source of this high precision, high stability only has two wires and during measuring, is connected in surveying instrument.During measuring, other wire, or is blocked by photoelectrical coupler by the cutting off with current source of physical property by relay.This constant current source has a variable clamp voltage from several volts to several hectovolts, and its steady current need to be less than 10% of LED working current.It is tested that this constant current source can be connected in LED(always) or only in measuring process, be connected in this tested LED.
This is without leakage, ripple disable and the mercury cut-off 30(SW that can switch fast) within the scope of whole clamp voltage, there is zero-leakage current, between transfer period, there is zero current or voltage fluctuation.Wherein, this mercury cut-off 30(SW) in measuring process, LED can be driven 60 electric currents switch to equivalent load 50 from LED, LED is driven 10 electric currents to switch to LED from equivalent load 50 after completing measurement, and be less than 20ms switching time.
The data-switching time of this data acquisition facility 20 need equal or faster than 10,000 reading/seconds (100us or better).When closing the drive current of this tested LED, this LED drives will be connected to an equivalent load 50.
Fig. 2 and Fig. 3 have shown respectively a LED equipment or COB(chip on board) measurement of junction temperature, and the measurement of a single LED junction temperature.
Fig. 4 has shown the performance of handoffs of mechanical relay and electronic relay.Wherein, electronic relay has a leakage current when high electricity volt, and mechanical relay has a fluctuating period, and is Millisecond the switching time of two kinds of relays.Therefore,, when LED junction temperature surveying instrument uses this relay, the accuracy of measurement will reduce greatly.
Fig. 5 has shown the performance of handoffs of a mercury cut-off 30.Can find out that the mercury cut-off that LED junction temperature surveying instrument of the present utility model uses does not have fluctuating period, there is no leakage current, and there is the quick switching time of Microsecond grade.Therefore, LED junction temperature surveying instrument of the present utility model has high measurement degree of accuracy.
Fig. 6 has shown the LED electric current while not having an equivalent load.This LED is driven by a constant current source, and for some drive units, when not loading, its output voltage will be very high.During measuring, this LED drives and need to disconnect with LED and become the zero load stage, and when drive unit is switched back to LED, the high voltage on LED will produce an electric current spark in LED, and this can damage this LED and cause temperature fluctuation.For some drive units; it has a holding circuit; when not loading; drive unit can cut out output current, and during measuring, this LED drives 60 need to cut off LED and become the zero load stage; now this drive unit will cut off output current; when switching this drive unit and get back to LED, this drive unit need to be reset to again drives this LED, can produce like this one do not have drive current during.Therefore, this will cause more temperature fluctuation.This equivalent load not this shows, if will be difficult to the junction temperature of continuous this LED of measurement.
Fig. 7 has shown the LED electric current while having an equivalent load.During measuring, this LED drives 60 to switch to this equivalent load, and therefore, this drive unit can not have a high output voltage or in protected mode.When this drive unit of switching is got back to LED, can generation current spark yet.In addition, also during the non-drive current of neither one.So, when thering is an equivalent load, the junction temperature of LED junction temperature surveying instrument energy continuous coverage one LED of this utility model and do not have temperature fluctuation or introduce an additional error.
This LED is semiconductor equipment, and a semiconductor is exactly a thermometer, and this semiconductor junction point voltage (forward voltage) is directly related with this LED junction temperature, and this LED node voltage is also directly related with this LED junction temperature.Therefore, node voltage is measured the measurement that can be used to LED junction temperature.
For the little drive current LED of milliampere level, a constant current source always connecting may be introduced some mistakes.Therefore LED junction temperature surveying instrument of the present utility model has used a constant current source of controlling according to the time to reduce measuring error.
Fig. 8 has shown the Measuring Time chart of this utility model.Order is as follows:
1) connect this steady current to this tested LED,
2) etc. to stable,
3) when this steady current (voltage) is stablized, by switch (SW) being adjusted to equivalent load, closing LED and drive and start to receive data before 60 electric currents,
4) after data acquisition completes, drive 60 electric currents from this equivalence load switching to LED this LED,
5) steady current is disconnected from tested LED.
If large 50 times than this steady current of this LED working currents, the measuring error being caused by steady current is minimum.Therefore, this constant current source can be connected in this system or tested LED always and not need to control.
The method of the LED junction temperature that measuring current source connects is always:
1) open data acquisition facility and receive data (node forward voltage),
2) by switch (SW) is switched to equivalent load from LED, close this LED and drive 60 electric currents,
3), when this data acquisition completes, LED drive current is switched to LED from equivalent load.
Fig. 9 has shown when the very fast data sink of neither one, how to improve data accuracy.Shown in Fig. 9, to the first data point, there is a time lag when switch activated.The poorest in the situation that, be to add the data acquisition time switching time this time lag.The data acquisition time of a low-cost data acquisition device is in 100us left and right.If be 20us left and right this switching time, be 120us left and right whole time lag.Therefore, owing to will causing a measuring error this time lag.As shown in the figure, 3 data points should be at least received, from these data points, temperature droop line can be found.The temperature data calculating is the point of crossing of temperature droop line and switch activated line (vertically).When using rapid data receiving trap, this temperature droop line is identical, and therefore, this point of crossing is also identical.
In order to obtain accurate a measurement, the background noise that is 50Hz or 60Hz such as frequency often throws into question, so zero cross detection and the data method of average used conventionally, but this method performance difficulty and cost are high.In the utility model, during data acquisition, this constant current source only has two wires to be connected to measuring system, and other all wires all physically disconnect with constant current source during data acquisition.This control line is blocked by photoelectrical coupler (not being conventional photo-coupler).The noise that there is no 50Hz or 60Hz in the data of this surveying instrument.
For verification, can not keep current source to connect can not be by computer control current source always.
Self-verification and K line thereof while keeping current source to connect always:
1) under room temperature (by thermocouple measurement), according to shown in Fig. 1 to Fig. 3 by LED or many LED(COB), or LED equipment is to this instrument, but do not connect LED, drives 60.
2), after temperature stabilization, open data acquisition facility to measure the first data (node forward voltage) point with inner constant current source.
3), in mobile LED or many LED or LED equipment to one baking box, adjust the temperature of this baking box extremely higher than 50 ℃ of room temperatures (preferably higher than working temperature).
4) according to step 2 to obtain the second data point.
5) use the first data (voltage/temperature) and the second data point (voltage/temperature) to create a K line chart, this K line chart is the relation between temperature and tested LED forward voltage.
There is time control constant current source oneself's verification and K line thereof:
1) under room temperature (by thermocouple measurement), according to shown in Fig. 1 to Fig. 3 by LED or many LED(COB), or LED equipment is to this instrument, but do not connect LED, drives 60.
2), after temperature stabilization, according to the flow process of Fig. 8, obtain the first data (node forward voltage) point.
3), in mobile LED or many LED or LED equipment to one baking box, adjust the temperature of this baking box extremely higher than 50 ℃ of room temperatures (preferably higher than working temperature).
4) according to step 2, obtain the 2nd LED forward voltage.
5) use the first data (voltage/temperature) and the second data point (voltage/temperature) to create a K line chart, this K line chart is the relation between temperature and tested LED forward voltage.
Those skilled in the art can understand that the utility model embodiment shown in accompanying drawing and described above is only to example of the present utility model rather than restriction.
Can see that thus the utility model object can fully effectively be completed.For explaining that this embodiment of the utility model function and structure principle has been absolutely proved and described, and the utility model is not subject to the restriction of the change based on these embodiment principle bases.Therefore, the utility model comprises all modifications being encompassed within appended claims book claimed range and spirit.
Claims (12)
1. a LED junction temperature surveying instrument, is characterized in that, comprising:
One forward voltage drop detecting unit;
One data acquisition facility;
One mercury cut-off; With
One LED drives, and wherein said LED drives as constant current source, and wherein said data acquisition facility can be switched on and is connected with described voltage drop detection unit; Wherein said mercury cut-off can drive LED node to be measured to switch to an equivalent load from LED in measuring process, and after completing measurement, described LED node is switched to described LED driving from described equivalent load.
2. LED junction temperature surveying instrument according to claim 1, is characterized in that, is less than 20ms the switching time of described mercury cut-off.
3. LED junction temperature surveying instrument according to claim 1, is characterized in that, described LED junction temperature surveying instrument can provide an equivalent load, and wherein said equivalent load is connected in described LED and drives during measuring.
4. LED junction temperature surveying instrument according to claim 2, is characterized in that, described LED junction temperature surveying instrument can provide an equivalent load, and wherein said equivalent load is connected in described LED and drives during measuring.
5. LED junction temperature surveying instrument according to claim 1, it is characterized in that, further comprise an electric power supply apparatus, wherein said electric power supply apparatus can be switched on and is connected with described data acquisition facility with described mercury cut-off respectively, and can provide electric energy for described mercury cut-off and described data acquisition facility.
6. LED junction temperature surveying instrument according to claim 4, it is characterized in that, further comprise an electric power supply apparatus, wherein said electric power supply apparatus can be switched on and is connected with described data acquisition facility with described mercury cut-off respectively, and can provide electric energy for described mercury cut-off and described data acquisition facility.
7. LED junction temperature surveying instrument according to claim 1, it is characterized in that, further comprise a data transmission interface, wherein said data transmission interface can be connected with described data acquisition facility with switching on, and the data in described data acquisition facility can be downloaded by described data transmission interface.
8. LED junction temperature surveying instrument according to claim 6, it is characterized in that, further comprise a data transmission interface, wherein said data transmission interface can be connected with described data acquisition facility with switching on, and the data in described data acquisition facility can be downloaded by described data transmission interface.
9. LED junction temperature surveying instrument according to claim 1, is characterized in that, further comprises that a thermal coupling thermometer is for measuring room temperature.
10. LED junction temperature surveying instrument according to claim 8, is characterized in that, further comprises that a thermal coupling thermometer is for measuring room temperature.
11. LED junction temperature surveying instruments according to claim 1, it is characterized in that, wherein during measuring, described LED drives only to be had two ports to switch on to be connected in described forward voltage drop detecting unit, and other port is physically driven and disconnects with described LED by relay, or is blocked by photoelectrical coupler.
12. LED junction temperature surveying instruments according to claim 10, it is characterized in that, wherein during measuring, described LED drives only to be had two ports to switch on to be connected in described forward voltage drop detecting unit, and other port is physically driven and disconnects with described LED by relay, or is blocked by photoelectrical coupler.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201420151595.6U CN203869783U (en) | 2014-01-29 | 2014-03-31 | Low-cost high-precision LED node temperature measuring instrument |
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| CN201420056313.4 | 2014-01-29 | ||
| CN201420056313 | 2014-01-29 | ||
| CN201420151595.6U CN203869783U (en) | 2014-01-29 | 2014-03-31 | Low-cost high-precision LED node temperature measuring instrument |
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| CN203869783U true CN203869783U (en) | 2014-10-08 |
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| CN201420151595.6U Expired - Fee Related CN203869783U (en) | 2014-01-29 | 2014-03-31 | Low-cost high-precision LED node temperature measuring instrument |
| CN201410127408.5A Pending CN104807552A (en) | 2014-01-29 | 2014-03-31 | Low-cost high-precision LED node temperature measuring instrument |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104807552A (en) * | 2014-01-29 | 2015-07-29 | 上海力兹照明电气有限公司 | Low-cost high-precision LED node temperature measuring instrument |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US20220074795A1 (en) * | 2018-12-25 | 2022-03-10 | Ozyegin Universitesi | System for measuring junction temperature of photonics devices |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1125988C (en) * | 2001-02-28 | 2003-10-29 | 山东大学 | Steady-state service life test method by controlling junction temp of transistor |
| US7010440B1 (en) * | 2003-11-25 | 2006-03-07 | Analog Devices, Inc. | Method and a measuring circuit for determining temperature from a PN junction temperature sensor, and a temperature sensing circuit comprising the measuring circuit and a PN junction |
| CN2901333Y (en) * | 2005-10-14 | 2007-05-16 | 北京工业大学 | Temperature rise and heat resistance detector of semiconductor PN junction diode device |
| US8278831B2 (en) * | 2008-01-28 | 2012-10-02 | Nxp B.V. | LED driver circuit and method, and system and method for estimating the junction temperature of a light emitting diode |
| CN102193053B (en) * | 2010-03-08 | 2013-10-09 | 上海时代之光照明电器检测有限公司 | Method for measuring relation curve of forward voltage and junction temperature of LED (Light Emitting Diode) in lamp |
| CN102072783B (en) * | 2010-11-18 | 2012-08-29 | 上海第二工业大学 | Method for testing junction temperature of LED |
| CN202794445U (en) * | 2012-09-05 | 2013-03-13 | 天津海瑞电子科技有限公司 | Novel high-temperature reverse bias testing machine |
| CN203869783U (en) * | 2014-01-29 | 2014-10-08 | 上海力兹照明电气有限公司 | Low-cost high-precision LED node temperature measuring instrument |
-
2014
- 2014-03-31 CN CN201420151595.6U patent/CN203869783U/en not_active Expired - Fee Related
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104807552A (en) * | 2014-01-29 | 2015-07-29 | 上海力兹照明电气有限公司 | Low-cost high-precision LED node temperature measuring instrument |
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