In recent years, with the continuous development of LED technology, high-power semiconductor lighting devices have been rapidly developed in recent years. In particular, white light power and light efficiency have been continuously improved, and LEDs have gradually entered the lighting field, triggering a new revolution in lighting technology. . LED is arranged in different ways and optical design, forming a wide range of LED lighting products, and LED lighting product research and development in China are in full swing, LED lighting products, performance levels are gradually increasing. Under the premise of adopting correct test methods, accurate measurement of photoelectric color performance parameters of LED lighting products is the basis for scientific evaluation of product performance, quality status and development trend. In view of the status quo of the detection of photoelectric color performance of LED lighting products, the author has combed and summarized the detection methods of the photoelectric color performance of LED lighting products by combining the accumulation of LED lighting products at the center.
First, the general evaluation of LED lighting product performance indicators
1. Classification of LED lighting products
At present, LED lighting products can be mainly divided into LED lighting fixtures (such as: LED street lighting, LED flood lighting, embedded LED lighting, LED tunnel lighting, LED decorative lighting, LED table lamps) and traditional lighting source replacement LED lamps (eg: Self-ballasted LED lamps, MR16, PAR lamps, straight tubular LED fluorescent lamps T8/T12, etc.). An LED lighting fixture is a complete lighting fixture that includes an LED-based light emitting element and a matching driver, a light distribution member, a fixing and protection light emitting element, and an appliance connected to the branch circuit member. Lighting LED lights can be divided into non-integrated LED lights and integral LED lights [10].
Non-integrated LED lamps contain LED arrays (modules) or LED packages (elements) and standard lamp bases, as well as other photometric, thermal, mechanical and electrical components. The LED lamp needs to be installed in a lamp with a standard lamp holder and LED driver. The LED light cannot be directly connected to the branch circuit.
Integral LED lamps contain an entire array of LED arrays (modules) or LED packages (elements), LED drivers, standard lamp caps, and other photometric, thermal, mechanical, and electrical components. The LED lamp can be mounted directly on a standardized lamp holder, which can be directly connected to the branch circuit. The biggest difference between LED lamps and LED lighting fixtures is that LED lamps need to be installed in standard lamp holders.
2. Difference between LED lighting fixtures and traditional light fixtures
At present, LED lighting and traditional light fixtures are different in many aspects. First of all, the life of traditional light fixtures can meet the requirements by replacing damaged light sources and lamp control devices, so the life of traditional light fixtures is generally not evaluated. LED lighting fixtures are integrated with the LED light source and the lamp housing. Currently, the lifespan of LED lighting fixtures is related to many factors such as the life of the LED light source itself, the LED driver, and the environment that the lamp provides to the LED. For different LED luminaires, their lifetime can only be determined by the evaluation of the relevant life characteristics.
Secondly, unlike traditional light fixtures, LED light fixtures use multiple LED light sources or module light emitters to make up and emit light. There are color differences between the light emitters in LED fixtures, and it is necessary to use color space evenness evaluation to evaluate LED fixtures. The spatial distribution of the color is used to evaluate the difference in the color of different observation angles of the LED lamps.
Again, conventional lighting sources can be used for photometric testing alone, and photometric measurements can use relative methods. Due to the integration of LED lamps and the extremely sensitive temperature of the LED light source, it is not suitable to separate the LED light source from the lamp for separate measurement. When the photometric measurement is performed, the photometric test should be performed on the LED lamp as a whole.
Fourth, traditional lighting fixtures are evaluated using lamp efficiency, while LED fixtures are evaluated using energy efficiency or light efficiency.
3. General evaluation of performance indicators of LED lighting products
The general evaluation content of the lighting product performance index mainly includes: optical characteristics; electrical characteristics, color characteristics, thermal characteristics, life characteristics, reliability, and the like. The current evaluation of LED lighting product performance indicators mainly includes the following aspects:
(1) The light characteristics mainly include: light intensity distribution, initial output energy efficiency (light efficiency)/light flux, light intensity/illuminance;
(2) The electrical characteristics mainly include: lamp power, power factor;
(3) The color characteristics mainly include: correlated color temperature, color rendering index, color product coordinates, color product tolerance, dominant wavelength (monochrome), color distribution inhomogeneity, and color space uniformity;
(4) Thermal properties mainly include thermal resistance and junction temperature;
(5) Lifetime characteristics mainly include switching frequency test, life/acceleration life test, lumen maintenance rate (light flux maintenance rate)/strength maintenance (reflecting cup type MR16 or PAR lamp);
(6) Reliability test.
Second, LED lighting products photoelectric color performance testing method
As the current standards on the thermal characteristics, life characteristics and reliability of LED lighting products are being studied and drafted, this article focuses on the detection methods of the photoelectric color performance of LED lighting products. The following sub-LED lighting and LED lights to discuss the two major series.
1. LED lighting product test environment and physical conditions
LED lighting products often have optical components, so they should be stored and tested in a relatively clean environment. The lens on the product should be clean and free of fingerprints. The test environment must not have excessive vibration and shocks, reducing air convection. Since the performance parameters of LED lighting products are relatively sensitive to temperature, the ambient air temperature and humidity during the test should meet the environmental requirements specified in the corresponding standards. The ambient temperature is 25 °C ± 1 °C (switch life test is 5 °C ± 5 °C) The maximum relative humidity is 65%, no convection. The working posture of the product shall be in accordance with the working posture or actual use attitude specified by the manufacturer, so as to avoid improper working posture affecting the heat dissipation, thereby affecting the photoelectric parameters. LED lighting products need long enough time to reach temperature balance. General LED lights need to be stable for 30 minutes, and large LED lighting fixtures need more than 2 hours to reach temperature equilibrium. The principle of judgment of temperature balance: if the illumination changes within 15 minutes is less than 0.5%, the temperature equilibrium can be considered.
2. LED lighting lamp photoelectric color performance testing
The main parameters of the photoelectric color performance of LED lighting include: total power of the lamp, power factor, light intensity distribution, total output luminous flux of the lamps, output luminous efficiency, lumen maintenance rate/ luminous flux maintenance rate, correlated color temperature, color rendering index, color tolerance, Color coordinates, spatial heterogeneity of chromaticity, etc.
(1) Results of all performance parameters can be obtained by one measurement on a goniophotometer equipped with a distributed spectroradiometer. The distributed spectroradiometer mainly tests the color characteristics and color space distribution of the lamps. The distribution photometer mainly tests the light distribution, luminous flux and other parameters. The test principle of the distribution photometer can refer to the standard GB/T 9468-2008 "General Requirements for Luminosity Distribution Photometry".
(2) At present, the light characteristics parameters (light distribution, luminous flux) and color characteristic parameters of many detection mechanisms are measured using a distributed photometer and an integrating sphere system, respectively. When using a distributed photometer to test fixtures, the lamp fixture must be such that the center of the LED fixture coincides with the center of the mechanical axis, and at the same time, the fixture is as normal as possible. When using the integrating sphere system to test color characteristics, the luminaire does not have to be in the center of the integrating sphere.
(3) The luminous flux of LED lamps can also be measured using an integrating sphere system. Ideally, the LED lamp should be placed on the top of the integrating sphere, and all the output light should enter the integrating sphere. At the same time, the color parameters of the lamps can be measured. At present, most of the existing open positions of the integrating spheres are on the side. For this reason, we have purchased the rotating 2-meter integrating sphere system of the United States Blue Philosophy for the light color detection of LED lighting products. The 2p opening of the integrating sphere can be stopped at any position as needed, so that the sample to be measured can be measured at any position and meet the ENERGY STAR LM-79 test requirement.
At present, the detection mechanism mainly uses the above-mentioned (1) and (2) modes for the detection of the photoelectric color performance of the LED lamp. The biggest drawback of measuring with a distributed photometer is that the test time is too long and the test efficiency is too low.
3. LED lamp photoelectric color performance testing
The main parameters of the photoelectric color performance of the LED lamp include: lamp power, power factor, luminous flux, output luminous efficiency, luminous flux maintenance rate, correlated color temperature, color rendering index, color product tolerance, color coordinates, and beam of a reflective cup type MR16 or PAR lamp Angle, light intensity, and light intensity maintenance rate.
(1) The integrating sphere system with an auxiliary lamp can quickly measure all these photoelectric color performance parameters of the LED lamp. First place the LED lamp in the center of the integrating sphere, and test it with the auxiliary lamp lit when the LED lamp under test is not lit. Extinguish the auxiliary lamp and light the LED lamp under test, and then test it once again to obtain the color characteristic parameters of the lamp under test, and automatically calculate the luminous flux of the LED lamp under test. If the integrating sphere does not have an auxiliary lamp, the LED lamp body itself will absorb some of the reflected light, and there will be some errors in the luminous flux value. At the same time, the inner sphere of the integrating sphere should also have a higher reflectance: 90% to 98%. At present, most of the integrating sphere systems in the testing institutions do not have auxiliary lights, and the reflectivity of the inner wall of the integrating sphere is less than 90%. These integrating sphere systems cannot accurately measure the luminous flux of LED lamps.
(2) The luminous flux of the LED lamp can also be measured with a goniophotometer. The range of gamma angle is 180° when the test is performed. The lamp center coincides with the center of the mechanical axis. The disadvantage is that the test time is too long.
(3) The beam angle and intensity of the reflective cup type MR16 or PAR lamp can be measured with a small bedroom distribution photometer. When testing, the mechanical axis and the optical axis should be the same. The disadvantage is that the test gesture is abnormal and the test result must be corrected.
Third, summary
The measurement of photoelectric color performance parameters of LED lighting products can be measured with a distributed photometer or an integrating sphere system, and can also be used together. Which method is specifically selected depends on the amount of measurement (color characteristics, light characteristics), the size of the product, and other requirements. In general, an integrating sphere system with an auxiliary lamp is suitable for measuring the light characteristics and color characteristic parameters of an integrated LED lamp and a relatively small-sized LED lamp. The advantage of the integrating sphere system test is that the measurement is fast and no dark room is required. The distribution photometer provides a method for measuring light intensity distribution and total luminous flux. It can measure relatively large LED lighting products and can of course also be used to measure small-sized LED lighting products. Pay attention to the test environment requirements, air flow may affect the measurement of temperature sensitive LED lighting products. The use of distribution photometer method should pay attention to correct clamping positioning. High-precision spectroradiometers mounted on a goniophotometer measure the spatial distribution of color directly without mirror reflection. Compared to integrating spheres, measuring with a goniophotometer takes more time. Under the premise of correct test methods, through the reasonable choice of detection methods to accurately measure the photoelectric color performance parameters of LED lighting products, to provide scientific support for scientific evaluation of the status and development trend of LED lighting product quality and development. (The full text is selected from "Semiconductor Lighting" magazine, Issue 9, 2011, editor: maysoong)
references
[1] GB/T 9468-2008 "General Requirements for Photometric Measurements of Luminaire Distribution"
[2] GB/T 7002-2008 "Luminescence Measurement for Cast Lighting Fixtures"
[3]IES LM-79-08 "Electrical and Photometric Measurements of Solid-State Lighting Products"
[4]IES LM-80-08 "Measurement of LED Light Source Lumen Maintenance Rate"
[5] GB/T 24824-2009 "Test Methods for LED Modules for General Lighting"
[6] GB/T 24908-2010 "performance requirements for self-ballasted LED lamps for general lighting"
[7]GB/T 24907-2010 "Road Lighting LED Performance Requirements"
[8]GB/T 24909-2010 "LED lamp for decorative lighting"
[9] Shi Xiaohong, “The Test Method for Solid State Lighting Products (SSL) Energy Star Certification†by the US Department of Energy (DOE)
[10] Chen Chaozhong, "The Characteristics and Standard Analysis of LED Lamps"
First, the general evaluation of LED lighting product performance indicators
1. Classification of LED lighting products
At present, LED lighting products can be mainly divided into LED lighting fixtures (such as: LED street lighting, LED flood lighting, embedded LED lighting, LED tunnel lighting, LED decorative lighting, LED table lamps) and traditional lighting source replacement LED lamps (eg: Self-ballasted LED lamps, MR16, PAR lamps, straight tubular LED fluorescent lamps T8/T12, etc.). An LED lighting fixture is a complete lighting fixture that includes an LED-based light emitting element and a matching driver, a light distribution member, a fixing and protection light emitting element, and an appliance connected to the branch circuit member. Lighting LED lights can be divided into non-integrated LED lights and integral LED lights [10].
Non-integrated LED lamps contain LED arrays (modules) or LED packages (elements) and standard lamp bases, as well as other photometric, thermal, mechanical and electrical components. The LED lamp needs to be installed in a lamp with a standard lamp holder and LED driver. The LED light cannot be directly connected to the branch circuit.
Integral LED lamps contain an entire array of LED arrays (modules) or LED packages (elements), LED drivers, standard lamp caps, and other photometric, thermal, mechanical, and electrical components. The LED lamp can be mounted directly on a standardized lamp holder, which can be directly connected to the branch circuit. The biggest difference between LED lamps and LED lighting fixtures is that LED lamps need to be installed in standard lamp holders.
2. Difference between LED lighting fixtures and traditional light fixtures
At present, LED lighting and traditional light fixtures are different in many aspects. First of all, the life of traditional light fixtures can meet the requirements by replacing damaged light sources and lamp control devices, so the life of traditional light fixtures is generally not evaluated. LED lighting fixtures are integrated with the LED light source and the lamp housing. Currently, the lifespan of LED lighting fixtures is related to many factors such as the life of the LED light source itself, the LED driver, and the environment that the lamp provides to the LED. For different LED luminaires, their lifetime can only be determined by the evaluation of the relevant life characteristics.
Secondly, unlike traditional light fixtures, LED light fixtures use multiple LED light sources or module light emitters to make up and emit light. There are color differences between the light emitters in LED fixtures, and it is necessary to use color space evenness evaluation to evaluate LED fixtures. The spatial distribution of the color is used to evaluate the difference in the color of different observation angles of the LED lamps.
Again, conventional lighting sources can be used for photometric testing alone, and photometric measurements can use relative methods. Due to the integration of LED lamps and the extremely sensitive temperature of the LED light source, it is not suitable to separate the LED light source from the lamp for separate measurement. When the photometric measurement is performed, the photometric test should be performed on the LED lamp as a whole.
Fourth, traditional lighting fixtures are evaluated using lamp efficiency, while LED fixtures are evaluated using energy efficiency or light efficiency.
3. General evaluation of performance indicators of LED lighting products
The general evaluation content of the lighting product performance index mainly includes: optical characteristics; electrical characteristics, color characteristics, thermal characteristics, life characteristics, reliability, and the like. The current evaluation of LED lighting product performance indicators mainly includes the following aspects:
(1) The light characteristics mainly include: light intensity distribution, initial output energy efficiency (light efficiency)/light flux, light intensity/illuminance;
(2) The electrical characteristics mainly include: lamp power, power factor;
(3) The color characteristics mainly include: correlated color temperature, color rendering index, color product coordinates, color product tolerance, dominant wavelength (monochrome), color distribution inhomogeneity, and color space uniformity;
(4) Thermal properties mainly include thermal resistance and junction temperature;
(5) Lifetime characteristics mainly include switching frequency test, life/acceleration life test, lumen maintenance rate (light flux maintenance rate)/strength maintenance (reflecting cup type MR16 or PAR lamp);
(6) Reliability test.
Second, LED lighting products photoelectric color performance testing method
As the current standards on the thermal characteristics, life characteristics and reliability of LED lighting products are being studied and drafted, this article focuses on the detection methods of the photoelectric color performance of LED lighting products. The following sub-LED lighting and LED lights to discuss the two major series.
1. LED lighting product test environment and physical conditions
LED lighting products often have optical components, so they should be stored and tested in a relatively clean environment. The lens on the product should be clean and free of fingerprints. The test environment must not have excessive vibration and shocks, reducing air convection. Since the performance parameters of LED lighting products are relatively sensitive to temperature, the ambient air temperature and humidity during the test should meet the environmental requirements specified in the corresponding standards. The ambient temperature is 25 °C ± 1 °C (switch life test is 5 °C ± 5 °C) The maximum relative humidity is 65%, no convection. The working posture of the product shall be in accordance with the working posture or actual use attitude specified by the manufacturer, so as to avoid improper working posture affecting the heat dissipation, thereby affecting the photoelectric parameters. LED lighting products need long enough time to reach temperature balance. General LED lights need to be stable for 30 minutes, and large LED lighting fixtures need more than 2 hours to reach temperature equilibrium. The principle of judgment of temperature balance: if the illumination changes within 15 minutes is less than 0.5%, the temperature equilibrium can be considered.
2. LED lighting lamp photoelectric color performance testing
The main parameters of the photoelectric color performance of LED lighting include: total power of the lamp, power factor, light intensity distribution, total output luminous flux of the lamps, output luminous efficiency, lumen maintenance rate/ luminous flux maintenance rate, correlated color temperature, color rendering index, color tolerance, Color coordinates, spatial heterogeneity of chromaticity, etc.
(1) Results of all performance parameters can be obtained by one measurement on a goniophotometer equipped with a distributed spectroradiometer. The distributed spectroradiometer mainly tests the color characteristics and color space distribution of the lamps. The distribution photometer mainly tests the light distribution, luminous flux and other parameters. The test principle of the distribution photometer can refer to the standard GB/T 9468-2008 "General Requirements for Luminosity Distribution Photometry".
(2) At present, the light characteristics parameters (light distribution, luminous flux) and color characteristic parameters of many detection mechanisms are measured using a distributed photometer and an integrating sphere system, respectively. When using a distributed photometer to test fixtures, the lamp fixture must be such that the center of the LED fixture coincides with the center of the mechanical axis, and at the same time, the fixture is as normal as possible. When using the integrating sphere system to test color characteristics, the luminaire does not have to be in the center of the integrating sphere.
(3) The luminous flux of LED lamps can also be measured using an integrating sphere system. Ideally, the LED lamp should be placed on the top of the integrating sphere, and all the output light should enter the integrating sphere. At the same time, the color parameters of the lamps can be measured. At present, most of the existing open positions of the integrating spheres are on the side. For this reason, we have purchased the rotating 2-meter integrating sphere system of the United States Blue Philosophy for the light color detection of LED lighting products. The 2p opening of the integrating sphere can be stopped at any position as needed, so that the sample to be measured can be measured at any position and meet the ENERGY STAR LM-79 test requirement.
At present, the detection mechanism mainly uses the above-mentioned (1) and (2) modes for the detection of the photoelectric color performance of the LED lamp. The biggest drawback of measuring with a distributed photometer is that the test time is too long and the test efficiency is too low.
3. LED lamp photoelectric color performance testing
The main parameters of the photoelectric color performance of the LED lamp include: lamp power, power factor, luminous flux, output luminous efficiency, luminous flux maintenance rate, correlated color temperature, color rendering index, color product tolerance, color coordinates, and beam of a reflective cup type MR16 or PAR lamp Angle, light intensity, and light intensity maintenance rate.
(1) The integrating sphere system with an auxiliary lamp can quickly measure all these photoelectric color performance parameters of the LED lamp. First place the LED lamp in the center of the integrating sphere, and test it with the auxiliary lamp lit when the LED lamp under test is not lit. Extinguish the auxiliary lamp and light the LED lamp under test, and then test it once again to obtain the color characteristic parameters of the lamp under test, and automatically calculate the luminous flux of the LED lamp under test. If the integrating sphere does not have an auxiliary lamp, the LED lamp body itself will absorb some of the reflected light, and there will be some errors in the luminous flux value. At the same time, the inner sphere of the integrating sphere should also have a higher reflectance: 90% to 98%. At present, most of the integrating sphere systems in the testing institutions do not have auxiliary lights, and the reflectivity of the inner wall of the integrating sphere is less than 90%. These integrating sphere systems cannot accurately measure the luminous flux of LED lamps.
(2) The luminous flux of the LED lamp can also be measured with a goniophotometer. The range of gamma angle is 180° when the test is performed. The lamp center coincides with the center of the mechanical axis. The disadvantage is that the test time is too long.
(3) The beam angle and intensity of the reflective cup type MR16 or PAR lamp can be measured with a small bedroom distribution photometer. When testing, the mechanical axis and the optical axis should be the same. The disadvantage is that the test gesture is abnormal and the test result must be corrected.
Third, summary
The measurement of photoelectric color performance parameters of LED lighting products can be measured with a distributed photometer or an integrating sphere system, and can also be used together. Which method is specifically selected depends on the amount of measurement (color characteristics, light characteristics), the size of the product, and other requirements. In general, an integrating sphere system with an auxiliary lamp is suitable for measuring the light characteristics and color characteristic parameters of an integrated LED lamp and a relatively small-sized LED lamp. The advantage of the integrating sphere system test is that the measurement is fast and no dark room is required. The distribution photometer provides a method for measuring light intensity distribution and total luminous flux. It can measure relatively large LED lighting products and can of course also be used to measure small-sized LED lighting products. Pay attention to the test environment requirements, air flow may affect the measurement of temperature sensitive LED lighting products. The use of distribution photometer method should pay attention to correct clamping positioning. High-precision spectroradiometers mounted on a goniophotometer measure the spatial distribution of color directly without mirror reflection. Compared to integrating spheres, measuring with a goniophotometer takes more time. Under the premise of correct test methods, through the reasonable choice of detection methods to accurately measure the photoelectric color performance parameters of LED lighting products, to provide scientific support for scientific evaluation of the status and development trend of LED lighting product quality and development. (The full text is selected from "Semiconductor Lighting" magazine, Issue 9, 2011, editor: maysoong)
references
[1] GB/T 9468-2008 "General Requirements for Photometric Measurements of Luminaire Distribution"
[2] GB/T 7002-2008 "Luminescence Measurement for Cast Lighting Fixtures"
[3]IES LM-79-08 "Electrical and Photometric Measurements of Solid-State Lighting Products"
[4]IES LM-80-08 "Measurement of LED Light Source Lumen Maintenance Rate"
[5] GB/T 24824-2009 "Test Methods for LED Modules for General Lighting"
[6] GB/T 24908-2010 "performance requirements for self-ballasted LED lamps for general lighting"
[7]GB/T 24907-2010 "Road Lighting LED Performance Requirements"
[8]GB/T 24909-2010 "LED lamp for decorative lighting"
[9] Shi Xiaohong, “The Test Method for Solid State Lighting Products (SSL) Energy Star Certification†by the US Department of Energy (DOE)
[10] Chen Chaozhong, "The Characteristics and Standard Analysis of LED Lamps"
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