Discussion: LED lighting product lumen attenuation causes

LED industry and current national advocate energy-saving environmental protection, create a green and low-carbon life policies, so get the strong support of governments, especially associated with public utilities (such as LED lamp etc.) is developing rapidly. But due to the constraints of cost and other factors, completely replace the traditional lighting in civilian areas, will take time. Due to fierce competition in the market, product replacement fast, shorten the development time has become an urgent need for the industry.

In November 11, 2013, thermal management and reliability technology branch, from the National Key Laboratory of semiconductor lighting joint R & D Engineer Lv Guangjun made entitled "CSA020 method measured the indoor LED lighting products causes lumen attenuation analysis" quick report. Lv Guangjun said: "compared with the traditional lighting products, as the third generation of LED lighting products are energy saving and environmental protection, long service life, safety, the appearance of good plasticity, flexible and easy to drive volume miniaturization and other advantages. LED industry and current national advocate energy-saving environmental protection, create a green and low-carbon life policies, so get the strong support of governments, especially associated with public utilities (such as LED lamp etc.) is developing rapidly. But due to the constraints of cost and other factors, completely replace the traditional lighting in civilian areas, will take time. Due to fierce competition in the market, product replacement fast, shorten the development time has become an urgent need for the industry. Therefore, national semiconductor lighting engineering research and Industry Alliance Standardization Committee (CSAS) to develop CSA020 "alliance standard released LED lighting products accelerated decay test method", is mainly applicable to LED lights, LED tunnel lamp, LED lamp, LED lamp, LED bulb lamp, LED lighting products.

The first is to accelerate the attenuation test method of accelerated CSA020 principle is guaranteed in the premise of precision test equipment, assuming the luminous maintenance rate and the time is e exponential decay relationship, you can use 3600 hours fluxattenuation data instead of the ES test methods required 6000 hours of data. In addition, the accelerated decay test method is used to demonstrate the feasibility of the Arrhenius acceleration model to describe the life of LED products at high junction temperature. Therefore, the method reduces the test time by increasing the ambient temperature (which is used to increase the LED junction temperature). In the proposed maximum temperature of 55 degrees Celsius test conditions, within 2000 hours of data, can be used to replace the ES method required room temperature data for 6000 hours. For the highest rated operating temperature of less than 55 degrees Celsius LED lighting products, the product requires the highest nominal operating temperature for the maximum test temperature. The feasibility and rationality of this method is proved not only in theory, but also by the actual test data of LED luminaire.

Discussion: LED lighting product lumen attenuation causes

The second is proposed by CSA020 standard inspection procedure is the use of sampling method, that is to say: the batch test using the same materials, components and light source, and have the same structure, continuous production in the same production line are composed of the batch test. Test samples shall be randomly selected from at least two manufacturing batches. The luminous flux of the sample should be stable. The sample sample in the accelerated test temperature, test box will be arranged in sequence into 4 test temperatures listed in Table 1, in each test temperature at least 60 minutes, the samples reach thermal equilibrium steady state, the optical properties of samples were measured in the temperature (such as illumination). At the end of each measurement, the sample should be taken out of the test chamber and placed at room temperature to measure the luminous flux when the sample is in a stable state. The samples in the temperature test box to measure the difference between the flux should be within 5%, the difference between the 4 optical properties set testing temperature measured in the temperature test box should be within 10%, can be the test temperature (25 DEG C except) decreased 5 as the accelerated decay test accelerated test temperature. Accelerated test should be used to meet the above conditions, the maximum accelerated test temperature, but should not be higher than 55 degrees, and should not be higher than the nominal maximum operating temperature. After the accelerated test, the sample needs to measure the initial luminous flux. The sample is then placed in the test chamber for accelerated testing. The test ambient temperature is determined by the accelerated test temperature and the relative humidity of the test environment is not more than 65%. Accelerated test to achieve the standard decision: CSA cited the nominal life expectancy of 25000 hours, 30000 hours and 35000 hours of the sample to determine the standard method. If the nominal life for 35000 hours in the sample, accelerate certain temperature, all samples reached the table 2 shows the total load time, accelerate the luminous maintenance rate of not less than 95%, while judging the minimum life expectancy sample reaches its nominal life 35000 hours. If the accelerated temperature is 55 DEG C, the LED lighting product life expectancy of 35000 hours, 30000 hours and 25000 hours, respectively, the test time is only 1750 hours, 1550 hours and 1300 hours. In order to verify the CSA020 "LED lighting products accelerated decay test method" is widely used, in the lamp, lamp, lamp bulb lamp, tunnel lamp and selected 17 kinds of representative LED lighting products are tested.

The results of accelerated decay test are consistent with the results of room temperature test at 55 degrees C and room temperature (25 degrees C). Compared with the United States Energy Star ES method, CSA020 "LED lighting products accelerated decay test method" can effectively shorten the life expectancy of LED lighting products test time required. The correctness of the theory of CSA020 test method and its wide representation have been verified by a large number of detailed data. Considering the accuracy of the measurement system, the test time can be shortened to 2000 hours at the test temperature of 55 DEG C.

CSA020 is currently being alliance national semiconductor lighting project, dozens of members of the unit received, I believe the near future will be more and more enterprises recognized, is bound to the LED lighting product development and industrial development play a huge role in promoting. The sample number is at least 3. The higher the number of samples, the higher the confidence of the results.