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Research on Detection Method of Photoelectric Color Performance of LED Lighting Products(II)

May 25, 2017

Fourth, the traditional lighting fixtures with lamp efficiency to evaluate, and LED lamps using energy efficiency or light efficiency to evaluate.

3.LED lighting product performance indicators of the general evaluation

The general evaluation of lighting product performance indicators include: optical characteristics; electrical characteristics, color characteristics, thermal characteristics, life characteristics, reliability and so on. The current evaluation of LED lighting product performance indicators include the following aspects.

(2) electrical characteristics mainly include: lamp power, power factor; (3) color characteristics include: related to the (1) light characteristics, including: light intensity distribution, the initial output energy efficiency (luminous efficiency) / luminous flux, light intensity / Color temperature, color rendering index, color coordinates, color difference, main wavelength (monochrome), color distribution unevenness and color space uniformity; (4) thermal characteristics include thermal resistance and junction temperature; Features include switch count test, life / accelerated life test, lumen maintenance rate (luminous flux maintenance rate) / light intensity maintenance rate (reflective cup type MR16 or PAR lamp); (6) reliability test.

 Second, LED lighting products, photoelectric color performance testing methods

As the current LED lighting products on the thermal characteristics, life characteristics and reliability of the relevant standards are being discussed and drafted, so this paper focuses on LED lighting products, photoelectric color performance testing methods. The following sub-LED lighting and LED lights to discuss the two series.

1.LED lighting product testing environment and physical conditions

LED lighting products often have optical components, so in a relatively clean environment to store and test, the lens on the product to be clean without fingerprints. The test environment can not have excessive shock and shock, reducing air convection. As the LED lighting product performance parameters are more sensitive to the temperature, in the test the surrounding ambient air temperature and humidity should meet the corresponding standards in the environmental requirements. Ambient temperature of 25 ℃ ± 1 (switch life test for 5 ℃ ± 5 ) maximum relative humidity of 65%, no convection wind. The working posture of the product should be in accordance with the provisions of the manufacturer's work attitude or the actual use of posture, so as not to affect the work posture affect the heat, and thus affect the photoelectric parameters. LED lighting products need a long enough time to achieve temperature balance. General LED lights to be stable for 30 minutes, large LED lighting to be more than 2 hours to reach the temperature balance. The principle of temperature balance to determine: within 15 minutes of illumination changes less than 0.5% can be considered to achieve a temperature balance.

2. LED lighting fixture photoelectric color performance detection

The main parameters of the LED lighting fixture include: the total power of the lamp, the power factor, the light intensity distribution, the total output luminous flux, the output light efficiency, the lumen maintenance rate / the luminous flux maintenance rate, the relevant color temperature, color rendering index, Color coordinates, color space unevenness and so on.

(1) The results of all the performance parameters are obtained by a single measurement on a distributed photometer with a distributed spectrum radiometer. The distribution spectrum radiometer 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. Distribution photometer test principle can refer to the standard GB / T 9468-2008 "luminous light distribution of the general requirements."

(2) At present, many of the detection mechanism of the optical characteristics of the parameters (light distribution, luminous flux) and color characteristics of the parameters were distributed spectrophotometer and integrating sphere system measured data. All the use of distributed photometer test lamps, the lamp clip must make LED light center and mechanical axis center coincide, while trying to make the lamp in the normal working posture. When using the integrating sphere system to test the color characteristics, the fixtures do not have to be in the center of the integrating sphere

(3) LED luminous flux can also be used to measure the ball system, the ideal state is to place the LED lights on the top of the integrating sphere, and make all the output light into the integrating sphere, but also can measure the color parameters of the lamp. At present, the existing integral ball opening position in the vast majority of the side, for which I specializes in the purchase of the United States Blue Philippines rotary 2-meter ball system for LED lighting products, light color detection. The 2p opening of the integrating sphere can be stopped at any position as needed to enable the measured sample to be measured at any position to meet the ENERGY STAR LM-79 test requirements.

At present, the detection mechanism for the LED light and light color performance testing mainly using the above (1), (2) two modes. The biggest drawback with a distributed photometer is that the test time is too long and the test efficiency is too low.

3. LED lights of the photoelectric color performance detection

The main parameters of the LED light and color performance include: lamp power, power factor, luminous flux, output luminous efficiency, luminous flux retention rate, correlated color temperature, color rendering index, color tolerance, color coordinates and reflector cup MR16 or PAR lamp Angle, light intensity and light intensity maintenance rate.

(1) Integral ball system with auxiliary lamp can quickly measure all of these photoelectric color performance parameters of LED lights. First LED lights placed in the center of the integrating sphere, LED lights are not lit in the case of light with aided lamp test once. Turn off the auxiliary lamp and light up the measured LED light, stable and then test once, get the color characteristics of the measured lights parameters, and automatically calculated by the software to be measured LED light flux. If the integral ball is not equipped with auxiliary lights, LED light body itself will absorb part of the reflected light, luminous flux value will be some error. While the integral ball wall should also have a high reflectivity: 90% to 98%. At present, most of the detection system within the integrating sphere system without auxiliary lights, integrating sphere wall reflectivity of less than 90%, these integrating ball system can not accurately measure the LED light flux.

(2) LED light flux can also be measured with a distributed photometer, test the angle range of γ to choose 180 °, the center of the lamp and the mechanical axis center coincidence. The disadvantage is that the test time is too long.

(3) Reflective cup type MR16 or PAR lamp beam angle, light intensity can be measured through a small bedroom distribution photometer. Test, the mechanical axis and optical axis to be consistent. The disadvantage is that the test posture is not working properly, the need to correct the test results.

Third, the summary

LED lighting products, photoelectric color performance parameters can be measured using a distributed photometer or integrating sphere system can also be used with. The specific method of choice depends on the amount of measurement required (color characteristics, optical characteristics), product size and other requirements. In general, an integrating sphere system with auxiliary lights is suitable for measuring the optical and color characteristics of an integrated LED and a relatively small size LED fixture. The advantage of the integrating sphere system test is that the measurement is quick and does not require a darkroom. The distribution photometer provides a light intensity distribution and total luminous flux measurement method, which can measure relatively large LED lighting products, of course, can also be used to measure small size LED lighting products. Note that the test environment requires that air flow may affect the measurement of temperature-sensitive LED lighting products. Use the distribution photometer method should pay attention to the correct clamping positioning. A high-precision spectral radiometer mounted on a distributed photometer can directly measure the spatial distribution of the color without mirroring. Compared with the integrating sphere, it is more time to use a distributed photometer to measure. Under the premise of correct test method, through the reasonable selection of detection methods to accurately measure the LED lighting products, photoelectric color performance parameters for the scientific evaluation of LED lighting product performance and quality of the status quo and development trends to provide data support.


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