CN102818651A - Detection method and detection circuit of LED (Light Emitting Diode) light source temperature - Google Patents
Detection method and detection circuit of LED (Light Emitting Diode) light source temperature Download PDFInfo
- Publication number
- CN102818651A CN102818651A CN2012102740213A CN201210274021A CN102818651A CN 102818651 A CN102818651 A CN 102818651A CN 2012102740213 A CN2012102740213 A CN 2012102740213A CN 201210274021 A CN201210274021 A CN 201210274021A CN 102818651 A CN102818651 A CN 102818651A
- Authority
- CN
- China
- Prior art keywords
- thermistor
- light source
- temperature
- led light
- resistance
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Landscapes
- Testing Of Individual Semiconductor Devices (AREA)
- Led Devices (AREA)
Abstract
The invention discloses a detection method and a detection circuit of an LED (Light Emitting Diode) light source temperature, wherein a constant current source is used for providing an accurate and stable current for a thermistor of an LED light source, thus, an influence that fluctuation of a supply voltage of the LED light source to computation of a resistance value of the thermistor is avoided; computation accuracy of the resistance value is improved; a computation process of the resistance value is simplified; and therefore, an accurate temperature of the LED light source can be obtained.
Description
Technical field
The present invention relates to the electronic circuit technology field, particularly relate to a kind of led light source temperature checking method and testing circuit.
Background technology
LED is regarded as the 21 century lighting source because of having advantages such as environmental protection, energy-conservation, life-span be long, and led light source has replaced conventional light source gradually and on various lightings, widely applied.In projector's industry, led light source is also used gradually and is replaced existing UHP bulb to become the light source of a new generation.
In the projector that adopts the R/G/B led light source; In order to guarantee that the final output brightness of projector reaches user's request for utilization; The power ratio of R/G/B led light source is bigger, and the light source power that generally is used for the LED of projector all reaches more than 100 watt, and pulse current is up to 36A.Under so big power, the thermal value of R/G/B led light source can be very big.And the serviceable life of LED and its working temperature have direct relation, and after temperature surpassed certain value, its brightness meeting descended greatly, and the life-span also descends greatly, and failure rate increases greatly.So, when high-power LED light source producer uses LED in this projector of design, all can R/G/B LED be encapsulated on the bigger copper base.Help the heat radiation of LED like this, simultaneously on this piece copper base, can lay thermistor again, can detect the working temperature of LED when making things convenient for downstream producer to use during this high-power LED light source in real time.According to the heat dissipation of this temperature adjustment cooling system, the working temperature that guarantees led light source is in OK range again for temperature when working through obtaining led light source in real time, system controller.Thereby guarantee the life-span of led light source.
Shown in Figure 1 is a kind of existing projector used R/G/B led light source temperature sensing circuit.In projector's course of work, can cooperate the peripheral temperature testing circuit, detect the working temperature of obtaining the R/G/B led light source in real time through controller.With R led light source temperature detection is example, and when working in projector, controller can obtain the voltage that A is ordered through the ADC analog to digital conversion circuit, is assumed to be U
AKnow U
AAfter, just can adopt formula (1), through resistance R S1 resistance and VCC supply voltage, calculate the resistance RT1 of thermistor this moment.
After calculating RT1; Just can table look-up (RT resistance and vs. temperature table are arranged in the thermistor specifications) obtain the temperature of thermistor this moment; Through the thermal resistance and the power relation of thermistor and R led light source, just can calculate the temperature of R led light source this moment.In like manner can obtain the temperature of G LED and B led light source.
The shortcoming of above testing circuit:
1, accuracy in detection is lower, because can be known by formula (1), the resistance of the RT1 that calculates receives the influence of VCC precision and stability, and VCC also supplies with the R/G/B led light source of big current work when supplying RT1.During work, VCC has fluctuation.So, even if adopt high-precision ADC to guarantee to detect U
APrecision, but because the fluctuation of VCC finally can influence the RT1 value that calculates.
Though 2, R/G/B thermistor that led light source adopts is a same size; But the relation of resistance and temperature can be variant between each thermistor; So there are error in temperature and its actual temperature of the thermistor of finding according to the relation of listed resistance and temperature in the specifications.
Above-mentioned two shortcomings of testing circuit cause the accuracy of detection of led light source temperature not high.
Summary of the invention
The present invention proposes a kind of detection method and testing circuit of led light source temperature, to improve the accuracy of detection of led light source temperature.
A kind of detection method of led light source temperature comprises step:
The employing constant current source is that the thermistor of led light source provides electric current;
Measure the pressure drop of said thermistor;
According to the electric current of said constant current source output and the pressure drop of said thermistor, calculate the resistance of said thermistor;
According to the relation of thermistor resistance and temperature, obtain the corresponding temperature of resistance of said thermistor, again according to the thermal resistance of thermistor and led light source and the relation of power, calculate the temperature of said led light source.
A kind of testing circuit of led light source temperature comprises constant current source, drop measurement circuit, ADC change-over circuit and controller,
Said constant current source is connected with the thermistor of led light source;
Said drop measurement circuit is used to measure the pressure drop of said thermistor;
Said ADC change-over circuit is used for analog to digital conversion is carried out in the pressure drop that said drop measurement circuit records;
Said controller is used for the pressure drop of reading said thermistor from said ADC change-over circuit; According to the electric current of said constant current source output and the pressure drop of said thermistor; Calculate the resistance of said thermistor,, obtain the temperature corresponding with the resistance of the said thermistor that calculates according to the relation of thermistor resistance and temperature; According to the thermal resistance of thermistor and led light source and the relation of power, calculate the temperature of said led light source again.
The detection method of led light source temperature of the present invention and testing circuit; The employing constant current source is that the thermistor of led light source provides precise and stable electric current; Avoided the influence of the fluctuation of led light source supply voltage to the calculating of thermistor resistance; Improved the accuracy that resistance is calculated, simplified resistance computation process, thereby obtained the accurate temperature of led light source.
Description of drawings
Fig. 1 is existing led light source temperature sensing circuit synoptic diagram;
Fig. 2 is the schematic flow sheet of the detection method of led light source temperature of the present invention;
Fig. 3 is the circuit diagram of an embodiment of the testing circuit of led light source temperature of the present invention.
Embodiment
The influence that the present invention calculates the thermistor resistance for fear of the supply voltage instability improves the peripheral testing circuit of led light source, adopts constant current source to supply with the constant electric current of thermistor, thereby has improved the accuracy of detection of led light source temperature.Below in conjunction with accompanying drawing and the present invention of embodiment illustrated in detail.
The detection method of led light source temperature of the present invention, as shown in Figure 2, may further comprise the steps:
Step S1, employing constant current source are that the thermistor of led light source provides electric current;
Step S2, the pressure drop of measuring said thermistor;
Step S3, according to the electric current of said constant current source output and the pressure drop of said thermistor, calculate the resistance of said thermistor;
Step S4, according to the relation of thermistor resistance and temperature, obtain the corresponding temperature of resistance of said thermistor, again according to the thermal resistance of thermistor and led light source and the relation of power, calculate the temperature of said led light source.
After adopting constant current source to be the thermistor power supply, the electric current I that flows through thermistor is constant, then only need measure the voltage difference at thermistor two ends, can calculate the resistance of thermistor according to Ohm law.The computation process of the thermistor resistance that the light source of three kinds of colors of R/G/B is corresponding is identical, is example with the R led light source, and the resistance computing formula of its thermistor RT1 is following:
In the following formula, I representes the electric current of constant current source output, the electric current of thermistor RT1 in other words, U
RT1The pressure drop at expression thermistor RT1 two ends.
Calculate the resistance of RT1, just can table look-up according to the thermistor specifications obtains corresponding temperature value, through the thermal resistance and the power relation of thermistor and R led light source, just can calculate the temperature of R led light source this moment.
The corresponding relation of listed resistance and temperature is that the parameter with reference thermistor is that canonical measure gets in the thermistor specifications; Though the thermistor of led light source is identical with the specification of reference thermistor; But still there is nuance in the relation between resistance and the temperature; The temperature of the thermistor that gets of causing tabling look-up is inaccurate, and is unfavorable to the accuracy of detection that improves light-source temperature.For this reason, the present invention has increased the step that thermistor is compensated calibration, with the difference of reference thermistor in the thermistor of eliminating led light source and the specifications.
The essence of compensation calibration is to make the pressure drop at thermistor two ends reach the standard of specifications through current compensation, even measured value equates that with theoretical value the constant current source that is adopted is the constant current source with fine adjustment function.The detailed process of compensation calibration is following: through the specifications of thermistor, inquire the standard resistance of thermistor under predetermined temperature (selecting 25 ℃ usually) with the thermistor same size of led light source, be designated as R
25 ℃The current settings of supposing constant-current source circuit is I, through these two parameters, just can calculate the pressure drop U of thermistor RT standard under 25 ℃ of states
25 ℃, U
25 ℃=R
25 ℃* I.Then, the projector of needs calibrations is placed on 25 ℃ constant-temperature house the inside, this moment, projector did not start shooting, and purpose is to make the temperature of the R/G/B of projector led light source consistent with environment temperature, also is 25 ℃.At last, open constant-current source circuit, but do not light the R/G/BLED light source, with the pressure drop U at Meter Test thermistor two ends
RT1, adjust the size of the output current of constant current source simultaneously, make the magnitude of voltage U that this moment, Meter Test arrived
RT1=U
25 ℃This has just accomplished the compensation calibration of R led light source thermistor testing circuit.After this, constant current source is that thermistor provides electric current according to adjusted electric current, but when calculating the resistance of thermistor, still adopts the electric current before the adjustment.
As a preferred embodiment, the pressure drop of adopting differential amplifier circuit to measure said thermistor two ends.
The testing circuit of led light source temperature of the present invention comprises constant current source, drop measurement circuit, ADC change-over circuit and controller.Said constant current source is connected with the thermistor of led light source; The input end of said drop measurement circuit is parallelly connected with thermistor, the said ADC change-over circuit of output termination, the pressure drop that is used to measure said thermistor; Said ADC change-over circuit carries out analog to digital conversion to the pressure drop that said drop measurement circuit records under the control of said controller; The pressure drop that said controller reads said thermistor from said ADC change-over circuit; According to the electric current of said constant current source output and the pressure drop of said thermistor; Calculate the resistance of said thermistor,, obtain the temperature corresponding with the resistance of the said thermistor that calculates according to the relation of thermistor resistance and temperature; According to the thermal resistance of thermistor and led light source and the relation of power, calculate the temperature of said led light source again.
In order to eliminate the individual difference of thermistor, said controller also is used to regulate the electric current of said constant current source output, makes the measured value of said thermistor pressure drop reach theoretical value,
Said measured value is to be in closed condition and to place to measure in the constant-temperature house of predetermined temperature at said led light source to get;
Said theoretical value is that the electric current of output before regulating according to said predetermined temperature, said constant current source and the relation calculating of thermistor resistance and temperature get.
As a preferred embodiment, said predetermined temperature is 25 ℃.
As a preferred embodiment, said drop measurement circuit is a differential amplifier circuit.
As a preferred embodiment, said constant current source is serially connected in said thermistor and with reference between the ground.
Based on above preferred embodiment, the physical circuit figure of this testing circuit is as shown in Figure 3.Detection method of the present invention is applied on the testing circuit of the present invention, can accurately detects the temperature of led light source, for follow-up heat radiation work provides the data support.
The above embodiment has only expressed several kinds of embodiments of the present invention, and it describes comparatively concrete and detailed, but can not therefore be interpreted as the restriction to claim of the present invention.Should be pointed out that for the person of ordinary skill of the art under the prerequisite that does not break away from the present invention's design, can also make some distortion and improvement, these all belong to protection scope of the present invention.Therefore, the protection domain of patent of the present invention should be as the criterion with accompanying claims.
Claims (9)
1. the detection method of a led light source temperature is characterized in that, comprises step:
The employing constant current source is that the thermistor of led light source provides electric current;
Measure the pressure drop of said thermistor;
According to the electric current of said constant current source output and the pressure drop of said thermistor, calculate the resistance of said thermistor;
According to the relation of thermistor resistance and temperature, obtain the corresponding temperature of resistance of said thermistor, again according to the thermal resistance of thermistor and led light source and the relation of power, calculate the temperature of said led light source.
2. the detection method of led light source temperature according to claim 1 is characterized in that, also comprises step: measure in said step before the pressure drop of said thermistor, said thermistor is compensated calibration, the process of compensation calibration is following:
According to the electric current and the resistance of said thermistor under predetermined temperature of said constant current source output, the pressure drop of calculating said thermistor obtains theoretical value;
Place in the constant-temperature house of said predetermined temperature down said led light source in off position;
Measure the pressure drop of said thermistor, regulate the electric current of said constant current source output, the measured value of said thermistor pressure drop is equated with said theoretical value,
Said constant current source is said thermistor power supply according to the electric current after regulating;
The electric current that said step is calculated the resistance institute basis of said thermistor is the electric current of output before said constant current source is regulated.
3. the detection method of led light source temperature according to claim 2 is characterized in that, said predetermined temperature is 25 ℃.
4. according to the detection method of claim 1 or 2 or 3 described led light source temperature, it is characterized in that the pressure drop of adopting differential amplifier circuit to measure said thermistor.
5. the testing circuit of a led light source temperature is characterized in that, comprises constant current source, drop measurement circuit, ADC change-over circuit and controller,
Said constant current source is connected with the thermistor of led light source;
Said drop measurement circuit is used to measure the pressure drop of said thermistor;
Said ADC change-over circuit is used for analog to digital conversion is carried out in the pressure drop that said drop measurement circuit records;
Said controller is used for the pressure drop of reading said thermistor from said ADC change-over circuit; According to the electric current of said constant current source output and the pressure drop of said thermistor; Calculate the resistance of said thermistor,, obtain the temperature corresponding with the resistance of the said thermistor that calculates according to the relation of thermistor resistance and temperature; According to the thermal resistance of thermistor and led light source and the relation of power, calculate the temperature of said led light source again.
6. the testing circuit of led light source temperature according to claim 5 is characterized in that, said controller also is used to regulate the electric current of said constant current source output, makes the measured value of said thermistor pressure drop reach theoretical value,
Said measured value is to be in closed condition and to place to measure in the constant-temperature house of predetermined temperature at said led light source to get;
Said theoretical value is that the electric current of output before regulating according to said predetermined temperature, said constant current source and the relation calculating of thermistor resistance and temperature get.
7. the testing circuit of led light source temperature according to claim 6 is characterized in that, said predetermined temperature is 25 ℃.
8. according to the testing circuit of claim 5 or 6 or 7 described led light source temperature, it is characterized in that said drop measurement circuit is a differential amplifier circuit.
9. according to the testing circuit of claim 5 or 6 or 7 described led light source temperature, it is characterized in that said constant current source is serially connected in said thermistor and with reference between the ground.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210274021.3A CN102818651B (en) | 2012-07-31 | 2012-07-31 | Detection method and detection circuit of LED (Light Emitting Diode) light source temperature |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210274021.3A CN102818651B (en) | 2012-07-31 | 2012-07-31 | Detection method and detection circuit of LED (Light Emitting Diode) light source temperature |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN102818651A true CN102818651A (en) | 2012-12-12 |
| CN102818651B CN102818651B (en) | 2014-07-02 |
Family
ID=47302910
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201210274021.3A Active CN102818651B (en) | 2012-07-31 | 2012-07-31 | Detection method and detection circuit of LED (Light Emitting Diode) light source temperature |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN102818651B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105717363A (en) * | 2016-04-06 | 2016-06-29 | 威胜集团有限公司 | Current loop impedance testing device of smart meter and impedance calculation method |
| CN112013986A (en) * | 2020-09-03 | 2020-12-01 | 珠海迈巨微电子有限责任公司 | Temperature detection circuit, temperature detection method and battery protection method |
| CN112461391A (en) * | 2020-11-11 | 2021-03-09 | 杭州仰仪科技有限公司 | Multi-channel thermistor iterative temperature measurement system in lithium battery isothermal calorimeter |
| CN114450033A (en) * | 2019-06-21 | 2022-05-06 | 路美康尔私人有限公司 | Method and device for monitoring the state of a high-level disinfection device |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201083556Y (en) * | 2007-10-25 | 2008-07-09 | 天津工业大学 | Trouble-proof temperature sensor |
| CN201285331Y (en) * | 2008-09-03 | 2009-08-05 | 伊玛精密电子（苏州）有限公司 | Pressure temperature sensor |
| US20100176746A1 (en) * | 2009-01-13 | 2010-07-15 | Anthony Catalano | Method and Device for Remote Sensing and Control of LED Lights |
| US20110031903A1 (en) * | 2008-01-28 | 2011-02-10 | Nxp B.V. | System and method for estimating the junction temperature of a light emitting diode |
-
2012
- 2012-07-31 CN CN201210274021.3A patent/CN102818651B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201083556Y (en) * | 2007-10-25 | 2008-07-09 | 天津工业大学 | Trouble-proof temperature sensor |
| US20110031903A1 (en) * | 2008-01-28 | 2011-02-10 | Nxp B.V. | System and method for estimating the junction temperature of a light emitting diode |
| CN201285331Y (en) * | 2008-09-03 | 2009-08-05 | 伊玛精密电子（苏州）有限公司 | Pressure temperature sensor |
| US20100176746A1 (en) * | 2009-01-13 | 2010-07-15 | Anthony Catalano | Method and Device for Remote Sensing and Control of LED Lights |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105717363A (en) * | 2016-04-06 | 2016-06-29 | 威胜集团有限公司 | Current loop impedance testing device of smart meter and impedance calculation method |
| CN114450033A (en) * | 2019-06-21 | 2022-05-06 | 路美康尔私人有限公司 | Method and device for monitoring the state of a high-level disinfection device |
| CN112013986A (en) * | 2020-09-03 | 2020-12-01 | 珠海迈巨微电子有限责任公司 | Temperature detection circuit, temperature detection method and battery protection method |
| CN112461391A (en) * | 2020-11-11 | 2021-03-09 | 杭州仰仪科技有限公司 | Multi-channel thermistor iterative temperature measurement system in lithium battery isothermal calorimeter |
Also Published As
| Publication number | Publication date |
|---|---|
| CN102818651B (en) | 2014-07-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102072783B (en) | Method for testing junction temperature of LED | |
| CN102818651B (en) | Detection method and detection circuit of LED (Light Emitting Diode) light source temperature | |
| JP2013524523A (en) | LED controller that compensates for die-to-die variation and temperature drift | |
| US20210010876A1 (en) | Method for calibrating short temperature measuring device using dry body temperature calibrator | |
| JP2013136298A (en) | Light emission driver device | |
| CN102435392A (en) | Remote intelligent pressure sensor calibration system | |
| CN104970776B (en) | A kind of body temperature detection method and a kind of Dynamic High-accuracy calibration electric body-temperature counter device | |
| CN102507046B (en) | Transformer thermometer calibrator | |
| JP6412669B2 (en) | Light emitting / receiving device and compensation method for light emitting / receiving device | |
| CN102519527A (en) | Thermal constant-power gas flow meter | |
| CN104713659A (en) | Thermistor resistance linear compensation circuit based on transistor output characteristic | |
| CN101788830B (en) | Digital temperature control circuit | |
| CN204274423U (en) | Clinical thermometer auto-calibration circuits | |
| KR102668952B1 (en) | Device and method for determining the power value of a target | |
| CN103196576A (en) | Junction temperature detection method for alternate current light-emitting diode (AC LED) based on peak current | |
| CN203629720U (en) | Thermal paint temperature detection device | |
| CN102138799B (en) | Wavelength compensation methods for high-accuracy blood oxygen probe | |
| CN104501980A (en) | Transformer winding temperature measuring device | |
| CN204556709U (en) | A kind of proving installation of nitrogen oxide sensor chip pumps electric current | |
| CN101236110A (en) | Luminous diode temperature tester | |
| TW202102054A (en) | System and method for calibrating a control system operating an electric heater | |
| CN208568102U (en) | A kind of High Precision Temperature Acquiring System | |
| CN203690702U (en) | Laser tube driving circuit for infrared sensor | |
| CN201673418U (en) | Controller capable of accurately setting the constant temperature point of constant temperature tank of constant temperature crystal oscillator from outside | |
| CN204313980U (en) | The temperature measuring equipment of Transformer Winding |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CP03 | Change of name, title or address |
Address after: 510670 Guangdong city of Guangzhou province Kezhu Guangzhou high tech Industrial Development Zone, Road No. 233 Patentee after: Wei Chong group Limited by Share Ltd Address before: 510663 Guangzhou province high tech Industrial Development Zone, Guangdong, Cai road, No. 6, No. Patentee before: Guangdong Weichuangshixun Science and Technology Co., Ltd. |
|
| CP03 | Change of name, title or address |