LEDs are a very long-lived source of light. Depending on the driving power supply and the conditions of use, LEDs can last up to 5W hours or more, but LEDs do not go out like other light sources, but gradually decay. Therefore, after a long period of use, light decay can result in low light output and the product does not meet the requirements. How to use TM-21 to estimate the life of LED lamps?
In order to give the LED industry a clearer concept of TM-21 and how to make good use of TM-21 to estimate LED products, we will explain the application and estimation of LM-80-08 and TM-21-11 in four procedures. the way:
Step 1: The LED component supplier performs an LM-80-08 experiment on its LED Source (Package/Array/Module) for 3 temperatures (55 ° C / 85 ° C / self-selected temperature) for at least 6,000 hours.
Number of samples required: (related to the estimable time)
Test time requirements: (connected with estimation accuracy)
At least 6,000 hours, recommended for 10,000 hours, the LED light attenuation data required to be tested every 1,000 hours, the shorter the interval (for example: 500 hours) can improve the accuracy of the estimation.
Step 2: Estimate the long-term life data of the three test temperatures (55 ° C / 85 ° C / optional temperature) according to the TM-21-11 formula.
Obtain the average value of each temperature experiment data, and the test data take-out time rule is:
The slope m (Slope) and the intercept b (Intercept) are obtained by Exponential Least Squares Curve-Fit. When m and b are calculated, the longer the test time is, the more dense the interval is, the higher the accuracy will be, and then the calculation will be performed. B and alpha values ​​are derived.
y=mx+b, B=exp(b), a=-m
The life time value of the LED of each temperature experiment at 70% of the lumen maintenance rate specified by ENERGY STAR was calculated according to the following formula.
L70 : Time of use when the LED lumen maintenance rate is 70%
The standard judgment of the multiple of the time can be estimated by the number of samples in the first step:
Expressed as: L70(6K) = XX, XXX hours
(6K) : LM-80 test time, (6K) = 6,000 hours; (10K) = 10,000 hours
XX, XXX Hours : Sample ≧20ea, test time = 6,000, can be estimated 6 times for 36,000 hours
Using the Exponential formula to calculate the lumen maintenance rate for each time, the calculated data can be calculated to plot the estimated life of each test temperature:
Step 3: Obtain the In Situ Temperature of the LED component placed on the LED lamp.
Please refer to the ISTMT (In Situ Temperature Measurement Test) test program to obtain the temperature of the LED component placed in the LED luminaire. The test temperature position must be the same as the Ts setting position of the LM-80-08. The temperature data taken out is called TMPLED (LED). Temperature Measurement Point).
Step 4: Interpolate the calculated results of the measured TMPLED and TM-21 calculations to obtain the estimated lifetime value of the TMPLED.
The two nearest temperature points of the TMPLED are selected from the three test temperature points as the calculation reference point.
Calculate the Arrhenius Model temperature acceleration parameter A and obtain Decay Rate: α and the setting parameter B0.
The L70 value of the TMPLED is calculated by the above formula, and the same program represents the result of the TMPLED.
L70(6K) > XX, XXX hours
Nest the relevant time values ​​and plot the lifetime estimation of TMPLED and three Ts.
Shanghai Lixin LEDLM-80PL luminous flux maintenance rate and aging test system is designed according to IESNA LM-80 standard, combined with Arrhenius model theory, so that users can predict L30, L70 through software after hundreds to thousands of hours of testing. Wait for the lumen maintenance rate.
Lihao Electronic Technology (Shanghai) Co., Ltd. is committed to the development and after-sales maintenance of lighting test instruments, EMI/EMC test systems and safety test instruments in the domestic market. Lisun's full range of products are developed and produced in strict accordance with ISO9001:2008 quality control requirements; Lisun is also a member of the Global Lighting CIE Association, all products meet the requirements of CIE; in addition, Lisun's products are CE certified and exported to the EU Qualifications.
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